Enigma

1

HE DOESN'T KNOW what wakes him – some faint sound, some movement in the air that hooks him in the depths of his dreams and hauls him to the surface.

At first his darkened room seems entirely normal – the familiar jet-black spar of the low oak beam, the smooth grey plains of wall and ceiling- but then he realises that a faint light is rising from the foot of his bed.

'Claire?' he says, propping himself up. 'Darling?'

'It's all right, darling. Go on back to sleep.'

'What on earth are you doing?'

'I'm just going through your things.'

'You're… what?'

His hand jumbles across the bedside table and switches on the lamp. His Waralarm shows him it is half past three.

'That's better,' she says, and she turns off the blackout torch. 'Useless thing, anyway.'

And she is doing exactly what she says. She is naked except for his shirt, she is kneeling, and she is going through his wallet. She removes a couple of one-pound notes, turns the wallet inside out and shakes it.

'No photographs?'she says.

'You haven't given me one yet.'

'Tom Jericho,' she smiles, replacing the money, I do declare, you 're becoming almost smooth.'

She checks the pockets of his jacket, his trousers then shuffles on her knees across to his chest of drawers. He laces his hands behind his head and leans back against the iron bedstead and watches her. It is only the second time they have slept together – a week after the first – and at her insistence they have done it not in her cottage but in his room, creeping through the darkened bar of the White Hart Inn and up the creaking stair. Jericho's bedroom is well away from the rest of the household so there is no danger of them being overheard. His books are lined up on the top of the chest of drawers and she picks up each in turn, holds it upside down and flicks through the pages.

Does he see anything odd in all this? No, he does not. It merely seems amusing, flattering, even – one further intimacy, a continuation of all the rest, a part of the waking dream his life has become, governed by dream rules. Besides, he has no secrets from her – or, at least, he thinks he hasn't. She finds Turing's paper and studies it closely.

'And what are computable numbers with an application to the Entscheidungsproblem, when they're at home?'

Her pronunciation of the German, he registers with surprise, is immaculate.

'It's a theoretical machine, capable of an infinite number of numerical operations. It supports the assumptions of Hilbert and challenges those of Godel. Come back to bed, darling.'

'But it's only a theory?'

He sighs and pats the mattress next to him. They're sleeping in a single bed. 'Turing believes there's no inherent reason why a machine shouldn't be capable of doing everything a human brain can do. Calculate. Communicate. Write a sonnet.'

'Fall in love?'

'If love is logical.'

'Is it?'

'Come to bed.'

'This Turing, does he work at the Park?'

He makes no reply. She leafs through the paper, squinting with disgust at the mathematics, then replaces it with the books and opens one of the drawers. As she leans forwards the shirt rides higher. The lower part of her back gleams white in the shadows. He stares, mesmerised, at the soft triangle of flesh at the base of her vertebrae as she rummages among his clothes.

'Ah, 'she says, 'now here is something. 'She withdraws a slip of paper. 'A cheque for a hundred pounds, drawn on the Foreign Office Contingency Fund, made out to you -'

'Give me that.'

'Why?'

'Put it back.'

He is across the room and standing beside her within a couple of seconds, but she is quicker than he is. She is on her feet, on tiptoe, holding the cheque aloft, and she -absurdly – is just that half-inch taller than him. The money flutters like a pennant beyond his reach.

I knew there would be something. Come on, darling, what's it for?'

He should have banked the damn thing weeks ago. He'd quite forgotten it. 'Claire, please

'You must have done something frightfully clever in that naval hut of yours. A new code? Is that it? You broke some new important code, my clever, clever darling?' She may be taller than he is, she may even be stronger, but he has the advantage of desperation. He seizes the firm muscle of her bicep and pulls her arm down and twists her round. They struggle for a moment and then he throws her back on the narrow bed. He prises the cheque out of her bitten-down fingers and retreats with it across the room.

'Notf unny, Claire. Some things just aren't that funny.'

He stands there on the rough matting- naked, slender, panting with exertion. He folds the cheque and slips it into his wallet, puts the wallet into his jacket, and turns to hang the jacket in the wardrobe. As he does so, he is aware of a peculiar noise coming from behind him – a frightening, animal noise, something between a rasping breath and a sob. She has curled herself up tight on the bed, her knees drawn up to her stomach, her forearms pressed to her face.

My God, what has he done?

He starts to gabble his apologies. He hadn 't meant to frighten her, let alone to hurt her. He goes across to the bed and sits beside her. Tentatively, he touches her shoulder. She doesn 't seem to notice. He tries to pull her towards him, to roll her over on her back, but she has become as rigid as a corpse. The sobs are shaking the bed. It is like a fit, a seizure. She is somewhere beyond grief, somewhere far away, beyond him.

'It's all right,' he says. 'It's all right.'

He can't tug the bedclothes out from under her, so he fetches his overcoat and lays that across her, and then he lies beside her, shivering in the January night, stroking her hair.

They stay like that for half an hour until, at last, when she is calm again, she gets up off the bed and begins to dress. He cannot bring himself to look at her and he knows better than to speak. He can just hear her moving around the room, collecting her scattered clothes. Then the door closes quietly. The stairs creak. A minute later he hears the click of her bicycle being wheeled away from beneath his window.

And now his own nightmare begins.

First, there is guilt, that most corrosive of emotions, more torturing even than jealousy (although jealousy is added to the brew a few days later, when he happens to see her walking through Bletchley with a man he doesn't recognise: the man could be anyone, of course – cousin, friend, colleague – but naturally his imagination can't accept that). Why did he respond so dramatically to so small a provocation; The cheque could, after all, have been a reward for anything. He didn 't have to tell her the truth. Now that she's gone, a hundred plausible explanations for the money come to mind. What had he done to provoke such terror in her? What awful memory had he reawakened?

He groans and draws the blankets over his head.

The next morning he takes the cheque to the bank and exchanges it for twenty large, crisp, white five-pound notes. Then he searches out the dreary little jewellery shop on Bletchley Road and asks for a ring, any ring as long as it is worth a hundred pounds, at which the jeweller – a ferret of a man with pebble-thick glasses, who clearly can't believe his luck -produces a diamond worth less than half that amount, and Jericho buys it.

He will make it up to her. He will apologise. It will all be right.

But luck is not with Jericho. He has become the victim of his own success. A Shark decrypt discloses that a U-boat tanker – the U-459, under Korvettenkapitan van Williamowitz-Mollendorf, with 700 tons of fuel on board – is to rendezvous with, and refuel, the Italian submarine Kalvi, 300 miles east of St Paul's Rock, in the middle of the Atlantic. And some fool at the Admiralty, forgetting that no action, however tempting, must ever be taken that will endanger the Enigma secret, orders a squadron of destroyers to intercept. The attack is made. It fails. The U-459 escapes. And Donitz, that crafty fox in his Paris lair, is immediately suspicious. In the third week of January, Hut 8 decrypts a series of signals ordering the U-boat fleet to tighten its cipher security. Shark traffic dwindles. There is barely enough material to make a menu for the bombes. At Bletchley, all leave is cancelled. Eight-hour shifts drag on to twelve hours, to sixteen hours… The daily battle to break the codes is almost as great a nightmare as it was in the depths of the Shark blackout, and Skynner's lash is felt on everybody s back.

Jericho's world has gone from perpetual sunshine to bleak midwinter in the space of a week. His messages to Claire, of entreaty and remorse, vanish, unanswered, into a void. He can't get out of the Hut to see her. He can't work. He can't sleep. And there's no one he can talk to. To Logie, lost and vague behind his smokescreen of tobacco? To Baxter, who would regard a dalliance with a woman like Claire Romilly as a betrayal of the world proletariat? To Atwood – Atwood! – whose sexual adventures have hitherto been confined to taking the prettier male undergraduates on golfing weekends to Brancaster, where they quickly discover that all the locks have been removed from the bathroom doors? Puck would have been a possibility, but Jericho could guess at his advice – 'Take out someone else, my dear Thomas, and fuck her' – and how could he admit the truth: that he didn 't want to 'fuck' anyone else, that he had never 'fucked' anyone else?

On the final day of January, collecting a copy of The Times from Brinklows the newsagent in Victoria Road, he spots her, at a distance, with the other man, and he shrinks into a doorway to avoid being seen. Apart from that, he never meets her: the Park has become too big, there are too many changes of shift. Eventually, he's reduced to lying in wait in the lane opposite her cottage, like a Peeping Tom. But she seems to have stopped coming home.

And then he almost walks right into her.

It is 8 February, a Monday, at four o'clock. He's walking wearily back to the hut from the canteen; she is part of a flood of workers streaming towards the gate at the end of the afternoon shift. He has rehearsed for his moment so many times, but in the end all he manages is a whine of complaint: 'Why don't you answer my letters?'

'Hello, Tom.'

She tries to walk on, but he won't let her get away this time. He has a pile of Shark intercepts waiting for him on his desk but he doesn't care. He catches at her arm.

I need to talk to you.'

Their bodies block the pavement. The flow of people has to pass around them, like a river round a rock.

'Mindout, 'says someone.

'Tom,' she hisses, 'for God's sake, you're making a scene.'

'Good. Let's get out of here.'

He is pulling at her arm. His pressure is insistent and reluctantly she surrenders to it. The momentum of the crowd sweeps them through the gate and along the road. His only thought is to put some distance between them and the Park. He doesn 't know how long they walk for – fifteen minutes, perhaps, or twenty – until, at last, the pavements are deserted and they are passing through the hinterland of the town. It is a raw, clear afternoon. On either side of them, semidetached suburban villas hide behind dirty privet hedges, their wartime gardens filled with chicken runs and the half-buried, corrugated-iron hoops of bomb shelters. She shakes her arm free. 'There's no point in this.'

'You 're seeing someone else?' He hardly dares to ask the question.

'I'm always seeing someone else.' He stops but she walks on. He lets her go for fifty yards then hurries to catch her up. By now the houses have petered out and they're in a kind of no-man's land between town and country, on Bletchley's western edge, where people dump their rubbish. A flock of seagulls cries and rises, like a swirl of waste paper caught by the wind. The road has dwindled to a track which leads under the railway to a row of abandoned Victorian brick kilns. Three red-brick chimneys, as in a crematorium, rise fifty feet against the sky. A sign says: DANGER, FLOODED CIAY PIT- VERY DEEP WATER.

Claire draws her coat around her shoulders and shivers – 'What a filthy place!' – but she still walks on ahead.

For ten minutes, the derelict brick works provide a welcome distraction. Indeed, they wander through the ruined kilns and workshops in a silence that is almost companionable. Amorous couples have scratched their formulae on the crumbling walls: AE + GS, Tony = Kath, Sal 4 Me. Lumps of masonry and brick litter the ground. Some of the buildings are open to the sky, the walls are scorched – there's clearly been afire – and Jericho wonders if the Germans could have mistaken it for a factory, and bombed it. He turns to say as much to Claire, but she has disappeared.

He finds her outside, her back to him, staring across the flooded clay pit. It is huge, a quarter of a mile across. The surface of the water is coal-black and perfectly still, the stillness hinting at unimaginable depths.

She says: 'I ought to get back.'

'What do you want to know?' he says. 'I'll tell you everything you want to know.'

And he will, if she wants it. He doesn't care about security or the war. He'll tell her about Shark and Dolphin and Porpoise. He'll tell her about the Bay of Biscay weather crib. He'll tell her all their little tricks and secrets, and draw her a diagram of how the bombe works, if that's what she wants. But all she says is: 'I do hope you're not going to be a bore about this, Tom.'

A bore. Is that what he is? He is being a bore?

'Wait,' he calls after her, 'you might as well have this.'

He gives her the little box with the ring in it. She opens it and tilts the stone to catch the light, then snaps the lid shut and hands it back.

'Not my style.'

'Poor you, 'he remembers her saying a minute or two later,

'I've really got under your skin, haven't I? Poor you…'

And by the end of the week he's in the deputy director's Rover, being borne back through the snow to King's.

2

The smells and sounds of an English Sunday breakfast curled up the staircase of the Commercial Guesthouse and floated across the landing like a call to arms: the hiss of hot fat frying in the kitchen, the dirge-like strains of a church service being relayed by the BBC, the muffled crack of Mrs Armstrong's worn slippers flapping like castanets on the linoleum floor.

They were a ritual in Albion Street, these Sunday breakfasts, served up with appropriate solemnity on plain white utility crockery: one piece of bread, as thick as a hymn book, dunked in fat and fried, with two spoonfuls of powdered egg, scrambled and slopped on top, the whole mass sliding freely on a rainbow film of grease.

It was not, Jericho had to acknowledge, a great meal, nor even a particularly edible one. The bread was rust-coloured, flecked with black, and obscurely flavoured by the kippers that had been cooked in the same fat the previous Friday. The egg was pale yellow and tasted of stale biscuits. Yet such was his appetite after the excitements of the night that, despite his anxiety, he ate every scrap of it, washed it down with two cups of greyish tea, mopped up the last of the grease with a fragment of bread, and even, on his way out, complimented Mrs Armstrong on the quality of her cooking – an unprecedented gesture which caused her to poke her head around the kitchen door and search his features for a trace of irony. She found none. He also attempted a cheerful 'Good morning' to Mr Bonnyman, who was just groping his way down the banisters ('Feeling a bit rough, to be honest, old boy -something wrong with the beer in that place') and by seven forty-five he was back in his room.

If Mrs Armstrong could have seen the changes he had wrought up there, she would have been astonished. Far from preparing to evacuate it after his first night, like so many of the bedroom's previous tenants, Jericho had unpacked. His suitcases were empty. His one good suit hung in the wardrobe. His books were lined along the mantelpiece. Balanced on the top of them was his print of King's College Chapel.

He sat on the edge of the bed and stared at the picture. It was not a skilful piece of work. In fact, it was rather ugly. The twin Gothic spires were hastily drawn, the sky was an improbable blue, the blob-like figures clustered around its base could have been the work of a child. But even bad art can sometimes have its uses. Behind its scratched glass, and behind the cheap Victorian mezzotint itself, laid flat and carefully secured, were the four undecrypted intercepts he had removed from Claire's bedroom.

He should have returned them to the Park, of course. He should have cycled straight from the cottage to the huts, should have sought out Logie or some other figure of authority, and handed them in.

Even now, he couldn't disentangle all his motives for not doing so, couldn't sort out the selfless (his wish to protect her) from the selfish (his desire to have her in his power, just once). He only knew he could not bring himself to betray her, and that he was able to rationalise this by telling himself that there was no harm in waiting till the morning, no harm in giving her a chance to explain.

And so he had cycled on, past the main gate, had tiptoed up to his room and had hidden the cryptograms behind the print, increasingly aware that he had strayed across whatever border it is that separates folly from treason, and that with every passing hour it would be harder for him to find his way back.

For the hundredth time, sitting on his bed, he ran though all the possibilities. That she was crazy. That she was being blackmailed. That her room was being used as a hiding place without her knowledge. That she was a spy.

A spy? The notion seemed fantastic to him -melodramatic, bizarre, illogical For one thing, why would a spy with any sense steal cryptograms? A spy would be after decodes, surely: the answers not the riddles; the hard proof that Enigma was being broken? He checked the door, then gently took down the picture and dismantled the frame, working the thumbtacks loose with his fingers and lifting away the hardboard backing. Now he thought about it, there was something distinctly odd about these cryptograms, looking at them again he realised what it was. They should have had the thin paper strips of decode produced by the Type-X machines gummed to their backs. But not only were there no strips, there weren't even any marks to show where the strips had been torn off. So, by the look of them, these signals had never even been broken. Their secrets were intact. They were virgin, None of it made any sense.

He stroked one of the signals between finger and thumb. The yellowish paper had a slight but perceptible odour. What was it? He held it close to his nose and inhaled. The scent of a library or an archive, perhaps? Quite a rich smell – warm, almost smoky – as evocative as perfume.

He realised suddenly that despite his fear he was actually beginning to treasure the cryptograms, as another man might treasure a favourite snapshot of a girl. Only these were better than any photographs, weren't they, for photographs were merely likenesses, whereas these were clues to who she was, and therefore wasn't he, by possessing them, in a sense, possessing her…? He would give her just one chance. No more. He looked at his watch. Twenty minutes had passed since breakfast. It was time to go. He slipped the cryptograms behind the picture, reassembled the frame and replaced it on the mantelpiece, then opened the door a fraction. Mrs Armstrong's regular guests had all come in from the night-shift. He could hear their murmured voices in the dining room. He put on his overcoat and stepped out on to the landing. Such were his efforts to seem natural, Mrs Armstrong would later swear she heard him humming to himself as he descended the stairs.

'I see you smiling in the cigarette glow

Though the picture fades too soon

But I see all I want to know

They can't black out the moon…'

From Albion Street to Bletchley Park was a walk of less than half a mile – left out of the door and along the street of terraced houses, left under the blackened railway bridge and sharp right across the allotments.

He strode quickly over the frozen ground, his breath steaming before him in the cold sunshine. Officially it was almost spring but someone had forgotten to pass the news on to winter. Patches of ice, not yet melted from the night before, cracked beneath the soles of his shoes. Rooks called from the tops of skeletal elms.

It was well past eight o'clock by the time he turned off the footpath into Wilton Avenue and approached the main gate. The shift change was over; the suburban road was almost deserted. The sentry – a giant young corporal, raw-faced from the cold – came stamping out of the guard post and barely glanced at his pass before waving him into the grounds.

Past the mansion he went, keeping his head down to avoid having to speak to anyone, past the lake (which was fringed with ice) and into Hut 8, where the silence emanating from the Decoding Room told him all he needed to know. The Type-X machines had worked their way through the backlog of Shark intercepts and now there was nothing for them to do until Dolphin and Porpoise came on stream, probably around mid-morning. He caught a glimpse of Logie's tall figure at the end of the corridor and darted into the Registration Room. There, to his surprise, was Puck, sitting in a corner, being watched by a pair of love-struck Wrens. His face was grey and lined, his head resting against the wall. Jericho thought he might be asleep but then he opened a piercing blue eye.

'Logie's looking for you.'

'Really?' Jericho took off his coat and scarf and hung them on the back of the door. 'He knows where to find me.'

'There's a rumour going around that you hit Skynner. For God's sake tell me it's true.'

One of the Wrens giggled.

Jericho had forgotten all about Skynner. He passed his hand through his hair. 'Do me a favour, Puck, will you?' he said. 'Pretend you haven't seen me?'

Puck regarded him closely for a moment, then shut his eyes. 'What a man of mystery you are,' he murmured, sleepily.

Back in the corridor Jericho walked straight into Logie.

'Ah, there you are, old love. I'm afraid we need to have a talk.'

'Fine, Guy. Fine.' Jericho patted Logie on the shoulder and squeezed past him. 'Just give me ten minutes.'

'No, not in ten minutes,' Logie shouted after him, 'now!'

Jericho pretended he hadn't heard. He trotted out into the fresh air, walked briskly round the corner, past Hut 6, towards the entrance to Hut 3. Only when he was within twenty paces of it did his footsteps slow, then stop.

The truth was, he knew very little about Hut 3, except that it was the place where the decoded messages of the German Army and Luftwaffe were processed. It was about twice the size of the other huts and was arranged in the shape of an L. It had gone up at the same time as the rest of the temporary buildings, in the winter of 1939 – a timber skeleton rising out of the freezing Buckinghamshire clay, clothed in a sheath of asbestos and flimsy wooden boarding – and to heat it, he remembered, they had cannibalised a big cast-iron stove from one of the Victorian greenhouses. Claire used to complain she was always cold. Cold, and that her job was 'boring'. But where exactly she worked within its warren of rooms, let alone what this 'boring' job entailed, was a mystery to him.

A door slammed somewhere behind him and he glanced over his shoulder to see Logie emerging from around the corner of the naval hut. Damn, damn. He dropped to one knee and pretended to fumble with his shoelace but Logie hadn't seen him. He was marching purposefully towards the mansion. That seemed to settle Jericho's resolve. Once Logie was out of sight, he counted himself down then launched himself across the path and through the entrance into the hut.

He did his best to look as if he had a right to be there. He pulled out a pen and set off down the central corridor, thrusting past airmen and Army officers, glancing officiously from side to side into the busy rooms. It was much more overcrowded even than Hut 8. The racket of typewriters and telephones was amplified by the membrane of wooden walls to create a bedlam of activity.

He had barely gone halfway down the passage when a colonel with a large moustache stepped smartly out of a doorway and blocked his path. Jericho nodded and tried to edge past him, but the colonel moved deftly to one side.

'Hold on, stranger. Who are you?'

On impulse Jericho stuck out his hand. 'Tom Jericho,' he said. 'Who are you?'

'Never mind who the hell I am.' The colonel had jug ears and thick black hair with a wide, straight parting that stood out like a firebreak. He ignored the proffered hand. 'What's your section?'

'Naval. Hut 8.'

'Hut 8? State your business here.'

'I'm looking for Dr Weitzman.'

An inspired lie. He knew Weitzman from the Chess Society: a German Jew, naturalised British, who always played Queen's Gambit Declined.

'Are you, by God?' said the colonel. 'Haven't you Navy people ever heard of the telephone?' He stroked his moustache and looked Jericho up and down. 'Well, you'd better come with me.'

Jericho followed the colonel's broad back along the passage and into a large room. Two groups of about a dozen men sat at tables arranged in a pair of semicircles, working their way through wire baskets stacked high with decrypts. Walter Weitzman was perched on a stool in a glass booth behind them.

'I say, Weitzman, d'you know this chap?'

Weitzman's large head was bent over a pile of German weapons manuals. He looked up, vague and distracted, but when he recognised Jericho his melancholy face brightened into a smile. 'Hello, Tom. Yes, of course I know him.'

'"Kriegsnachrichten Fur Seefahrer,'" said Jericho, a fraction too quickly. 'You said you might have something by now.'

For a moment, Weitzman didn't react and Jericho thought he was done for, but then the old man said slowly, 'Yes. I believe I have that information for you.' He lowered himself carefully from his stool. 'You have a problem, colonel?'

The colonel thrust his chin forward. 'Yes, actually, Weitzman, I do, now you mention it. "Inter-hut communication, unless otherwise authorised, must be conducted by telephone or written memorandum." Standard procedure.' He glared at Weitzman and Weitzman stared back, with exquisite politeness. The belligerence seemed to leak out of the colonel. 'Right,' he muttered. 'Yes. Remember that in future.'

'Arsehole,' hissed Weitzman, as the colonel moved away. 'Well, well. You'd better come over here.'

He led Jericho to a rack of card-index files, selected a drawer, pulled it out and began riffling through it. Every time the translators came across a term they couldn't understand, they consulted Weitzman and his famous index-system. He'd been a philologist at Heidelberg until the Nazis forced him to emigrate. The Foreign Office, in a rare moment of inspiration, had dispatched him to Bletchley in 1940. Very few phrases defeated him.

' "Kriegsnachrichten Fur Seefahrer," "War notices for Marines. "First intercepted and catalogued, November ninth last year. As you knew perfectly well already.' He held the card within an inch of his nose and studied it through his thick spectacles. Tell me, is the good colonel still looking at us?'

'I don't know. I think so.' The colonel had bent down to read something one of the translators had written, but his gaze kept returning to Jericho and Weitzman. 'Is he always like that?'

'Our Colonel Coker? Yes, but worse today, for some reason.' Weitzman spoke softly, without looking at Jericho. He tugged open another drawer and pulled out a card, apparently absorbed. 'I suggest we stay here until he leaves the room. Now here's a U-boat term we picked up in January: "Fluchttiefe."'

'"Evasion depth,"' replied Jericho. He could play this game for hours. Vorhalt-Rechner was a deflection-angle computer. A cold-soldered joint was a kalte Lotstelle. Cracks in a U-boat's bulkheads were Stirnwandrisse…

'"Evasion depth,"' Weitzman nodded. 'Quite right.'

Jericho risked another look at the colonel. 'He's going out of the door… now. It's all right. He's gone.'

Weitzman gazed at the card for a moment, then slipped it back among the rest and closed the drawer. 'So. Why are you asking me questions to which you already know the answers?' His hair was white, his small brown eyes overshadowed by a jutting forehead.

Wrinkles at their edges suggested a face that had once creased readily into laughter. But Weitzman didn't laugh much any more. He was rumoured to have left most of his family behind in Germany.

'I'm looking for a woman called Claire Romilly. Do you know her?'

'Of course. The beautiful Claire. Everyone knows her.'

'Where does she work?'

'She works here.'

'I know here. Here where?'

'"Inter-hut communication, unless otherwise authorised, must be conducted by telephone or written memorandum. Standard procedure.'" Weitzman clicked his heels. 'Heil Hitler!'

'Bugger standard procedure.'

One of the translators turned round, irritably. 'I say, you two, put a sock in it, will you?'

'Sorry.' Weitzman took Jericho by the arm and led him away. 'Do you know, Tom,' he whispered, 'in three years, this is the first time I have heard you swear?'

'Walter. Please. It's important.'

'And it can't wait until the end of the shift?' He gave Jericho a careful look. 'Obviously not. Well, well again. Which way did Coker go?'

'Back towards the entrance.'

'Good. Follow me.'

Weitzman led Jericho almost to the other end of the hut, past the translators, through two long narrow rooms where scores of women were labouring over a pair of giant card indexes, around a corner and through a room lined with teleprinters. The din here was terrific. Weitzman put his hands to his ears, looked over his shoulder and grinned. The noise pursued them down a short length of passage, at the end of which was a closed door. Next to it was a sign, in a schoolgirl's best handwriting: GERMAN BOOK ROOM.

Weitzman knocked on the door, opened it and went inside. Jericho followed. His eye registered a large room. Shelves stacked with ledgers and files. Half dozen trestle tables pushed together to form one big working area. Women, mostly with their backs to him. Six, perhaps, or seven? Two typing, very fast, the others moving back and forth arranging sheaves of papers into piles.

Before he could take in any more, a plump, harassed-looking woman in a tweed jacket and skirt advanced to meet them. Weitzman was beaming now, exuding charm, for all the world as if he were still in the tearoom of Heidelberg's Europaischer Hof. He took her hand and bowed to kiss it.

'Guten Morgen, mein liebes Fraulein Monk. Wie geht's?'

'Gut, danke, Herr Doktor. Und dir?'

'Danke, sehr gut.'

It was clearly a familiar routine between them. Her shiny complexion flushed pink with pleasure. 'And what can I do for you?'

'My colleague and I, my dear Miss Monk – ' Weitzman patted her hand, then released it and gestured towards Jericho '- are looking for the delightful Miss Romilly.'

At the mention of Claire's name, Miss Monk's flirtatious smile evaporated. 'In that case you must join the queue, Dr Weitzman. Join the queue.'

'I am sorry. The queue?'

'We are all trying to find Claire Romilly. Perhaps you, or your colleague, have an idea where we might start?'

To say that the world stands still is a solipsism, and Jericho knew it even as it seemed to happen – knew that it isn't ever the world that slows down, but rather the individual, confronted by an unexpected danger, who receives a charge of adrenaline and speeds up. Nevertheless, for him, for an instant, everything did freeze. Weitzman's expression became a mask of bafflement, the woman's of indignation. As his brain tried to compute the implications, he could hear his own voice, far away, begin to babble: 'But I thought… I was told – assured – yesterday – she was supposed to be on duty at eight this morning…"

'Quite right,' Miss Monk was saying. 'It really is most thoughtless of her. And terribly inconvenient.'

Weitzman gave Jericho a peculiar look, as if to say, What have you got me into? 'Perhaps she's ill?' he suggested.

'Then surely a note would have been considerate? A message? Before I let the entire night-shift go? We can barely cope when there are eight of us. When we're down to seven…'

She started to prattle on to Weitzman about '3A' and '3M' and all the staffing memos she'd written and how no one appreciated her difficulties. As if to prove her point, at that moment the door opened and a woman came in with a stack of files so high she had to wedge her chin on top of them to keep control. She let them fall on the table and there was a collective groan from Miss Monk's girls. A couple of signals fluttered over the edge of the table and on to the floor and Jericho, primed for action, swooped to retrieve them. He got a brief glimpse of one -

zzz BATTLE HEADQUARTERS GERMAN AFRIKA KORPS LOCATED MORNING THIRTEENTH? THIRTEENTH ONE FIVE KILOMETRES WEST OF BEN GARDANE? BEN GARDANE

– before it was snatched out of his hands by Miss Monk. She seemed for the first time to become aware of his presence. She cradled the secrets to her plump breast and glared at him.

'I'm sorry, you are – who are you exactly?' she asked. She edged to one side to block his view of the table. 'You are – what? – a friend of Claire, I take it?'

'It's all right, Daphne,' said Weitzman, 'he's a friend of mine.'

Miss Monk flushed again. 'I beg your pardon, Walter,' she said. 'Of course, I didn't mean to imply-'

Jericho cut in: 'I wonder, could I ask you, has she done this before? Failed to turn up, I mean, without telling you?'

'Oh no. Never. I will not tolerate slacking in my section. Dr Weitzman will vouch for that.'

'Indeed,' said Weitzman, gravely. 'No slacking here.'

Miss Monk was of a type that Jericho had come to know well over the past three years: mildly hysterical at moments of crisis; jealous of her precious rank and her extra fifty pounds a year; convinced that the war would be lost if her tiny fiefdom were denied a gross of lead pencils or an extra typist. She would hate Claire, he thought: hate her for her prettiness and her confidence and her refusal to take anything seriously.

'She hasn't been behaving at all oddly?'

'We have important work to do. We've no time here for oddness.'

'When did you last see her?'

'That would be Friday.' Miss Monk obviously prided herself on her memory for detail. 'She came on duty at four, went off at midnight. Yesterday was her rest day.'

'So I don't suppose it's likely she came back into the hut, say, early on Saturday morning?'

'No. I was here. Anyway, why should she do that? Normally, she couldn't wait to get away.'

I bet she couldn't. He glanced again at the girls behind Miss Monk. What on earth were they all doing? Each had a mound of paperclips in front of her, a pot of glue, a pile of brown folders and a tangle of rubber bands. They seemed – could this be right? – to be compiling new files out of old ones. He tried to imagine Claire here, in this drab room, among these sensible drones. It was like picturing some gorgeous parakeet in a cage full of sparrows. He wasn't sure what to do. He took out his watch and flicked open the lid. Eight thirty-five. She had already been missing more than half an hour.

'What will you do now?'

'Obviously – because of the level of classification – there's a certain procedure we have to follow. I've already notified Welfare. They'll send someone round to her room to turf her out of bed.'

'And if she isn't there?'

'Then they'll contact her family to see if they know where she is.'

'And if they don't?'

'Well, then it's serious. But it never gets that far.' Miss Monk drew her jacket tight across her pigeon chest and folded her arms. 'I'm sure there's a man at the bottom of this somewhere.' She shuddered. 'There usually is.'

Weitzman was continuing to give Jericho imploring glances. He touched him on the arm. 'We ought to go now, Tom.'

'Do you have an address for her family? Or a telephone number?'

'Yes, I think so, but I'm not sure I should…' She turned towards Weitzman, who hesitated fractionally, shot another look at Jericho, then forced a smile and a nod.

'I can vouch for him.'

'Well,' said Miss Monk, doubtfully, 'if you think it's permissible…' She went over to a filing cabinet beside her desk and unlocked it.

'Coker will kill me for this,' whispered Weitzman, while her back was turned.

'He'll never find out. I promise you.'

'The curious thing is,' said Miss Monk, almost to herself, 'that she'd really become much more attentive of late. Anyway, this is her card.'

Next-of-kin: Edward Romilly.

Relation: Father.

Address: 27 Stanhope Gardens, London SW.

Telephone: Kensington 2257.

Jericho glanced at it for a second and handed it back.

'I don't think there's any need to trouble him, do you?' asked Miss Monk. 'Certainly not yet. No doubt Claire will arrive at any moment with some silly story about oversleeping – '

'I'm sure,' said Jericho.

'- in which case,' she added shrewdly, 'who shall I say was looking for her?'

'Auf Wiedersehen, Fraulein Monk.' Weitzman had had enough. He was already half out of the room, pulling Jericho after him with surprising force. Jericho had a last vision of Miss Monk, standing bewildered and suspicious, before the door closed on her schoolroom German.

'Auf Wiedersehen, HerrDoktor, undHerr…'

Weitzman didn't lead Jericho back the way they had come. Instead he bundled him out of the rear exit. Now, in the cold daylight, Jericho could see why he had found it so difficult stumbling around out here the other night. They were on the edge of a building site. Trenches had been carved four feet deep into the grass. Pyramids of sand and gravel were covered in a white mould of frost. It was a miracle he hadn't broken his neck.

Weitzman shook a cigarette out of a crumpled pack of Passing Clouds and lit it. He leaned against the wall of the hut and exhaled a sigh of steam and smoke. 'Useless for me to ask, I suppose, what in God's name is going on?'

'You don't want to know, Walter. Believe me.'

'Troubles of the heart?'

'Something like that.'

Weitzman mumbled a couple of words in Yiddish that might have been a curse and continued to smoke.

About thirty yards away, a group of workmen were huddled around a brazier, finishing a tea break. They dispersed reluctantly, trailing pickaxes and spades across the hard ground, and Jericho had a sudden memory of himself as a boy, holding hands with his mother, walking along a seaside promenade, his spade clattering on the concrete road behind him. Somewhere beyond the trees, a generator kicked into life sending a scattering of rooks cawing into the sky.

'Walter, what's the German Book Room?'

'I'd better get back,' said Weitzman. He licked the ends of his thumb and forefinger and nipped off the glowing tip of his cigarette, slipping the unsmoked portion into his breast pocket. Tobacco was far too precious to waste even a few shreds.

'Please, Walter…'

'Ach!' Weitzman made a sudden gesture of disgust with his arm, as if sweeping Jericho aside, and began making his way, unsteadily but wonderfully quickly for a man of his age, down the side of the hut towards the path. Jericho had to scramble to keep pace with him.

'You ask too much, you know – '

'I know I do.'

'I mean, my God, Coker already suspects I am a Nazi spy. Can you believe that? I may be a Jew, but for him one German is no different from another. Which, of course, is precisely our argument. I suppose I should be flattered.'

'I wouldn't – it's just – there's nobody else…'

A pair of sentries with rifles rounded the corner and strolled towards them. Weitzman clamped his jaw shut and abruptly turned right off the path towards the tennis court. Jericho followed him. Weitzman opened the gate and they stepped on to the asphalt. The court had been put in – at Churchill's personal instigation, so it was said – two years earlier. It hadn't been used since the autumn. The white lines were barely visible beneath the frost. Drifts of leaves had collected against the chain-link fence. Weitzman closed the gate after them and walked towards the net post.

'It's all changed since we started, Tom. Nine-tenths of the people in the hut I don't even know any more.' He kicked moodily at the leaves and Jericho noticed for the first time how small his feet were; dancer's feet. 'I've grown old in this place. I can remember a time when we thought we were geniuses if we read fifty messages a week. Do you know what the rate is now?'

Jericho shook his head.

Three thousand a day.'

'Good God.' That's a hundred and twenty-five an hour, thought Jericho, that's one every thirty seconds…

'Is she in trouble, then, your girl?'

'I think so. I mean, yes – yes, she is.'

I'm sorry to hear it. I like her. She laughs at my jokes. Women who laugh at my jokes must be cherished. Especially if they are young. And pretty.'

'Walter…'

Weitzman turned towards Hut 3. He had chosen his ground well, with the instinct of a man who has been forced at some time, as a matter of personal survival, to learn how to find privacy. Nobody could come up behind them without entering the tennis court. Nobody could approach from the front without being seen. And if anyone was watching from a distance -well, what was there to see but two old colleagues, having a private chat?

'It's organised like a factory line.' He curled his fingers into the wire netting. His hands were white with cold. They clenched the steel like claws. 'The decrypts arrive by conveyor belt from Hut 6. They go first to the Watch for translation – you know that, that's my post. Two Watches per shift, one for urgent material, the other for back-breaks. Translated Luftwaffe signals are passed to 3A, Army to 3M. A for air, M for military. God in heaven, it's cold. Are you cold? I'm shaking.' He pulled out a filthy handkerchief and blew his nose. 'The duty officers decide what's important and give it a Z-priority. A single Z is low-grade – Hauptmann Fischer is to be transferred to the German Air Fleet in Italy. A weather report would be three Zs. Five Zs is pure gold – where Rommel will be tomorrow afternoon, an imminent air attack. The intelligence is summarised, then three copies are dispatched – one to SIS in Broadway, one to the appropriate service ministry in Whitehall, one to the relevant commander in the field.'

'And the German Book Room?'

'Every proper name is indexed: every officer, every piece of equipment, every base. For example, Hauptmann Fischer's transfer may at first seem quite worthless as intelligence. But then you consult the Air Index and you see his last posting was to a radar station in France. Now he is going to Bari. So: the Germans are installing radar in Bari. Let them build it. And then, when it is almost finished, bomb it.'

'And that's the German Book?'

'No, no.' Weitzman shook his head crossly, as if Jericho were some dim student at the bottom of his class at Heidelberg. 'The German Book is the very end of the process. All this paper – the intercept, the decode, the translation, the Z-signal, the list of cross-references, all these thousands of pages – it all comes together at the end to be filed. The German Book is a verbatim transcription of all decoded messages in their original language.'

'Is that an important job?'

'In intellectual terms? No. Purely clerical.'

'But in terms of access? To classified material?'

'Ah. Different.' Weitzman shrugged. 'It would depend on the person involved, of course, whether they could be bothered to read what they were handling. Most don't.'

'But in theory?'

'In theory? On an average day? A girl like Claire would probably see more operational detail about the German armed forces than Adolf Hitler.' He glanced at Jericho's incredulous face and smiled. 'Absurd, isn't it? What is she? Nineteen? Twenty?'

'Twenty,' muttered Jericho. 'She always told me her job was boring.'

'Twenty! I swear it's the greatest joke in the history of warfare. Look at us: the hare-brained debutante, the weakling intellectual and the half-blind Jew. If only the master race could see what we're doing to them -sometimes the thought of it is all that keeps me going.' He held his watch up very close to his face. 'I must get back. Coker will have issued a warrant for my arrest. I fear I have talked too much.'

'Not at all.'

'Oh, I have, I have.'

He turned towards the gate. Jericho made a move to follow but Weitzman held up a hand to stop him. 'Why don't you wait here, Tom? Just for a moment. Let me get clear.'

He slipped out of the court. As he passed by on the other side of the fence, something seemed to occur to him. He slowed and beckoned Jericho closer to the wire netting.

'Listen,' he said softly, 'if you think I can help you again, if you need any more information – please, don't ask me. I don't want to know.'

Before Jericho could answer he had crossed the path and disappeared around the back of Hut 3.

Within the grounds of Bletchley Park, just beyond the mansion, in the shadow of a fir tree, stood an ordinary red telephone box. Inside it, a young man in motorcycle leathers was finishing a call. Jericho, leaning against the tree, could hear his singsong accent, muffled but audible.

'Right you are… OK, doll… See you.'

The dispatch rider put the receiver down with a clatter and pushed open the door.

'All yours, pal.'

The motorcyclist didn't move away at first. Jericho stood in the kiosk, pretending to fish in his pockets for change, and watched him through the glass. The man adjusted his leggings, put on his helmet, fiddled with the chin strap…

Jericho waited until he had moved away before dialling zero.

A woman's voice said: 'Operator speaking.'

'Good morning. I'd like to make a call, please, to Kensington double-two five seven.'

She repeated the number. 'That'll be fourpence, caller.'

A sixty-mile land line connected all Bletchley Park numbers to the Whitehall exchange. As far as the operator could tell, Jericho was merely calling one London borough from another. He pressed four pennies into the slot and after a series of clicks he heard a ringing tone.

It took fifteen seconds for a man to answer.

'Ye-es?'

It was exactly the voice Jericho had always imagined for Claire's father. Languid and assured, it stretched that single short syllable into two long ones. Immediately there was a series of pips and Jericho pushed the A-button. His money tinkled into the coin-box.

Already, he felt at a disadvantage – an indigent without access to a telephone of his own.

'Mr Romilly?'

'Ye-es?'

'I'm so sorry to trouble you, sir, especially on a Sunday morning, but I work with Claire…'

There was a faint noise, and then a pause, during which he could hear Romilly breathing. A crackle of static cut across the line. 'Are you still there, sir?'

The voice, when it came again, was quiet, and it sounded hollow, as if emanating from a vast and empty room. 'How did you get this number?'

'Claire gave it me.' It was the first lie that came into Jericho's head. 'I wondered if she was with you.'

Another long pause. 'No. No, she isn't. Why should she be?'

'She's not turned up for her shift this morning. Yesterday was her day off. I wondered if she might have gone down to London.'

'Who is this speaking?'

'My name is Tom Jericho.' Silence. 'She may have spoken of me.'

'I don't believe so.' Romilly's voice was barely audible. He cleared his throat. 'I'm awfully sorry, Mr Jericho. I'm afraid I can't help you. My daughter's movements are as much a mystery to me as they seem to be to you. Goodbye.'

There was a fumbling noise and the connection was broken off.

'Hello?' said Jericho. He thought he could still hear somebody breathing on the line. 'Hello?' He held on to the heavy bakelite receiver for a couple of seconds, straining to hear, then carefully replaced it.

He leaned against the side of the telephone box and massaged his temples. Beyond the glass, the world went silently about its business. A couple of civilians with bowler hats and rolled umbrellas, fresh from the London train, were being escorted up the drive to the mansion. A trio of ducks in winter camouflage came in to land on the lake, feet splayed, ploughing furrows in the grey water.

'My daughter's movements are as much a mystery to me as they seem to be to you.'

That was not right, was it? That was not the reaction one would expect of a father on being told his only child was missing?

Jericho groped in his pocket for a handful of change. He spread the coins out on his palm and stared at them, stupidly, like a foreigner just arrived in an unfamiliar country.

He dialled zero again.

'Operator speaking.'

'Kensington double-two five seven.'

Once again, Jericho inserted four pennies into the metal slot. Once again there was a series of short clicks, then a pause. He tightened his finger on the button. But this time there was no ringing tone, only the blip-blip-blip of an engaged signal, pulsing in his ear like a heartbeat.

Over the next ten minutes Jericho made three more attempts to get through. Each met the same response.

Either Romilly had taken his telephone off the hook, or he was involved in a long conversation with someone.

Jericho would have tried the number a fourth time, but a woman from the canteen with a coat over her apron had turned up and started rapping a coin on the glass, demanding her turn. Finally, Jericho let her in. He stood on the roadside and tried to decide what to do.

He glanced back at the huts. Their squat, grey shapes, once so boring and familiar, now seemed vaguely threatening.

Damn it. What did he have to lose?

He buttoned his jacket against the cold and turned towards the gate.

3

St Mary's Parish Church, eight solid centuries of hard white stone and Christian piety, lay at the end of an avenue of elderly yew trees, less than a hundred yards beyond Bletchley Park. As Jericho walked through the gate he saw bicycles, fifteen or twenty of them, stacked neatly around the porch, and a moment later heard the piping of the organ and the mournful lilt of a Church of England congregation in mid-hymn. The graveyard was perfectly still. He felt like a late guest approaching a house where a party was already in full swing.

'We blossom and flourish as leaves on a tree, And wither, and perish, but naught changeth thee

Jericho stamped his feet and beat his arms. He considered slipping inside and standing at the back of the nave until the service ended, but experience had taught him there was no such thing as a quiet entry into a church. The door would bang, heads would turn, some officious sidesman would come hurrying down the aisle with a prayer sheet and a hymn book. Such attention was the last thing he wanted.

He left the path and pretended to study the tombstones. Frosted cobwebs of improbable size and delicacy shone like ectoplasm between the memorials: marble monuments for the well-to-do, slate for the farmworkers, weathered wooden crosses for the poor and infants. Ebenezer Slade, aged four years and six months, asleep in the arms of Jesus. Mary Watson, wife of Albert, taken after a long illness, rest in peace… On a few of the graves, bunches of dead flowers, petrified by ice, testified to some continuing flicker of interest among the living. On others, yellow lichen had obscured the inscriptions. He bent and scratched away at it, hearkening to the voices of the righteous beyond the stained glass window.

'O ye Dews and Frosts, bless ye the Lord: praise him and magnify him for ever.

O ye Frost and Cold, bless ye the Lord: praise him and magnify him for ever…"

Odd images chased through his mind.

He thought of his father's funeral, on just such a day as this: a freezing, ugly Victorian church in the industrial Midlands, medals on the coffin, his mother weeping, his aunts in black, everyone studying him with sad curiosity, and he all the time a million miles away, factoring the hymn numbers in his head ('Forward out of error,/Leave behind the night' – number 392 in Ancient and Modern -came out very prettily, he remembered, as 2 x 7 x 2 x 7 x 2…)

And for some reason he thought of Alan Turing, restless with excitement in the hut one winter night, describing how the death of his closest friend had made him seek a link between mathematics and the spirit, insisting that at Bletchley they were creating a new world: that the bombes might soon be modified, the clumsy electro-mechancial switches replaced by relays of pentode valves and GT1C-thyatrons to create computers, machines that might one day mimic the actions of the human brain and unlock the secrets of the soul…

Jericho wandered among the dead. Here was a small stone cross garlanded with stone flowers, there a stern-looking angel with a face like Miss Monk. All the time he kept listening to the service. He wondered whether anyone from Hut 8 was among the congregation and, if so, who. With all else failing, might Skynner be offering up a prayer to God? He tried to imagine what fresh reserves of sycophancy Skynner would draw on to communicate with a being even higher than the First Lord of the Admiralty, and found he couldn't do it.

'The blessing of God Almighty, the Father, the Son, and the Holy Ghost, be amongst you and remain with you always. Amen.'

The service was over. Jericho wove quickly through the headstones, away from the church, and stationed himself behind a pair of large bushes. From here he had a clear view of the porch.

Before the war the faithful would have emerged to an uplifting peal of grandsire triples. But church bells now were to be rung only in the event of invasion, so that when the door opened and the elderly priest stationed himself to say farewell to his parishioners, the silence gave the ceremony a subdued, even melancholy air. One by one the worshippers stepped into the daylight. Jericho didn't recognise any of them. He began to think he might have come to the wrong conclusion. But then, sure enough, a small, lean young woman in a black coat appeared, still holding the prayer book from the night before.

She shook hands briefly, even curtly, with the vicar, said nothing, looped her carpetbag over the handles of her bicycle and wheeled it towards the gate. She walked quickly, with short, rapid steps, her sharp chin held high. Jericho waited until she had gone some way past him, then stepped out from his hiding place and shouted after her: 'Miss Wallace!'

She stopped and glanced back in his direction. Her weak eyesight made her frown. Her head moved vaguely from side to side. It wasn't until he was within two yards of her that her face cleared.

'Why, Mr…'

'Jericho.'

'Of course. Mr Jericho. The stranger in the night.' The cold had reddened the sharp point of her nose and painted two neat discs of colour, the size of half-crowns, on her white cheeks. She had long, thick, black hair which she wore piled up, shot through and secured by an armoury of pins. 'What did you make of the sermon?'

'Uplifting?' he said, tentatively. It seemed easier than telling the truth.

'Did you really? I thought it the most frightful rot I've heard all year. "Suffer not a woman to teach, nor to usurp authority over the man, but to be in silence…"' She shook her head furiously. 'Is it a heresy, do you suppose, to call St Paul an ass?

She resumed her brisk progress towards the lane. Jericho fell in beside her. He had picked up a few details about Hester Wallace from Claire – that before the war she'd been a teacher at a girls' private school in Dorset, that she played the organ and was a clergyman's daughter, that she received the quarterly newsletter of the Jane Austen Society – just enough clues to suggest the sort of woman who might indeed go straight from an eight-hour night-shift to Sunday matins.

'Do you attend most Sundays?'

'Always,' she said. 'Although increasingly one wonders why. And you?'

He hesitated. 'Occasionally.'

It was a mistake and she was on to it at once.

'Whereabouts d'you sit? I don't recall ever seeing you.'

'I try to keep at the back.'

'So do I. Exactly at the back.' She gave him a second look, her wire-framed round spectacles flashing in the winter sun. 'Really, Mr Jericho, a sermon you obviously didn't hear, a pew you never occupy: one might almost suspect you of laying claim to a piety you don't rightly possess.'

'Ah…"

'I'll bid you good day.'

They had reached the gate. She swung herself on to the saddle of her bicycle with surprising grace. This was not how Jericho had planned it. He had to reach out and hold on to the handlebars to stop her pedalling away.

'I wasn't in church. I'm sorry. I wanted to talk to you.'

'Kindly remove your hand from my machine, Mr Jericho.' A couple of elderly parishioners turned to stare at them. 'At once, if you please.' She twisted the handlebars back and forth but Jericho held on.

'I am so sorry. It really won't take a moment.'

She glared at him. For an instant he thought she might be about to reach down for one of her stout and sensible shoes and hammer his fingers loose. But there was curiosity as well as anger in her eyes, and curiosity won. She sighed and dismounted.

'Thank you. There's a bus shelter over there.' He nodded to the opposite side of Church Green Road. 'Just spare me five minutes. Please.'

'Absurd. Quite absurd.'

The wheels of her bicycle clicked like knitting needles as they crossed the road to the shelter. She refused to sit. She stood with her arms folded, looking down the hill towards the town.

He tried to think of some way of broaching the subject. 'Claire tells me you work in Hut 6. That must be interesting.'

'Claire has no business telling you where I work. Or anyone else for that matter. And, no, it is not interesting. Everything interesting seems to be done by men. Women do the rest.'

She could be pretty, he thought, if she put her mind to it. Her skin was as smooth and white as Parian. Her nose and chin, though sharp, were delicate. But she wore no make-up, and her expression was permanently cross, her lips drawn into a thin, sarcastic line. Behind her spectacles, her small, bright eyes glinted with intelligence.

'Claire and I, we were…' He fluttered his hands and searched for the word. He was so hopeless at all this. '"Seeing one another" I suppose is the phrase. Until about a month ago. Then she refused to have anything more to do with me.' His resolution was wilted by her hostility. He felt a fool, addressing her narrow back. But he pressed on. 'To be frank, Miss Wallace, I'm worried about her.'

'How odd.'

He shrugged. 'We were an unlikely couple, I agree.'

'No.' She turned to him. 'I meant how odd that people always feel obliged to disguise their concern for themselves as concern for other people.'

The corners of her mouth twitched down in her version of a smile and Jericho realised he was beginning to dislike Miss Hester Wallace, not least because she had a point.

'I don't deny an element of self-interest,' he conceded, 'but the fact is, I am worried about her. I think she's disappeared.'

She sniffed. 'Nonsense.'

'She hasn't turned up for her shift this morning.'

'An hour late for work hardly constitutes a disappearance. She probably overslept.'

'I don't think she went home last night. She certainly wasn't back by two.'

'Then perhaps she overslept somewhere else,' said Miss Wallace, maliciously. The spectacles flashed gain. 'Incidentally, might I ask how you know she didn't come home?'

He had learned it was better not to lie. 'Because I let myself in and waited for her.'

'So. A housebreaker as well. I can see why Claire wants nothing more to do with you.'

To hell with this, thought Jericho.

'There are other things you should know. A man came to the cottage last night while I was there. He ran away when he heard my voice. And I just called Claire's father. He claims he doesn't know where she is, but I think he's lying.'

That seemed to impress her. She chewed on the inside of her lip and looked away, down the hill. A train, an express by the sound of it, was passing through Bletchley. A curtain of brown smoke, half a mile long, rose in percussive bursts above the town.

'None of this is my concern,' she said at last.

'She didn't mention she was going away?'

'She never does. Why should she?'

'And she hasn't seemed odd to you lately? Under any sort of strain?'

'Mr Jericho, we could probably fill this bus shelter -no, we could probably fill an entire double-decker bus – with young men who are worried about their relationships with Claire Romilly. Now I'm really very tired. Much too tired and inexpert in these matters to be of any help to you. Excuse me.'

For the second time she mounted her bicycle, and this time Jericho didn't try to stop her. 'Do the letters ADU mean anything to you?'

She shook her head irritably and pushed herself away from the kerb.

'It's a call sign,' he shouted after her. 'Probably German Army or Luftwaffe.'

She applied the brakes with such force she slid off the saddle, her flat heels skittering in the gutter. She looked up and down the empty road. 'Have you gone utterly mad?'

'You'll find me in Hut 8.'

'Wait a moment. What has this to do with Claire?'

'Or, failing that, the Commercial Guesthouse in Albion Street.' He nodded politely. 'ADU, Miss Wallace. Angels Dance Upwards. I'll leave you in peace.'

'Mr Jericho…'

But he didn't want to answer any of her questions. He crossed the road and hurried down the hill. As he turned left into Wilton Avenue towards the main gate he glanced back. She was still where he had left her, her thin legs planted either side of the pedals, staring after him in astonishment.

4

Logie was waiting for him when he got back to Hut 8. He was prowling around the confined space of the Registration Room, his bony hands clasped behind his back, the bowl of his pipe jerking around as he chomped furiously on its stem.

'This your coat?' was his only greeting. 'Better bring it with you.'

'Hello, Guy. Where are we going?' Jericho unhooked his coat from the back of the door and one of the Wrens gave him a rueful smile.

'We're going to have a chat, old cock. Then you're going home.'

Once inside his office, Logie threw himself into his chair and swung his immense feet up on to his desk. 'Close the door then, man. Let's at least try and keep this between ourselves.'

Jericho did as he was told. There was nowhere for him to sit so he leaned his back against it. He felt surprisingly calm. 'I don't know what Skynner's been telling you,' he began, 'but I didn't actually land a punch.'

'Oh, well, that's fine, then.' Logie raised his hands in mock relief. 'I mean to say, as long as there's no blood, none of your actual broken bones- '

'Come on, Guy. I never touched him. He can't sack me for that.'

'He can do whatever he sodding well likes.' The chair creaked as Logie reached across the desk and picked up a brown folder. He flicked it open. 'Let us see what we have here. "Gross insubordination," it says. "Attempted physical assault," it says. "Latest in a long series of incidents which suggest the individual concerned is no longer fit for active duties."' He tossed the file back on his desk. 'Not sure I disagree, as a matter of fact. Been waiting for you to show your face around here ever since yesterday afternoon. Where've you been? Admiralty? Taking a swing at the First Sea Lord?'

'You said not to work a full shift. "Just come and go as you please." Your very words.'

'Don't get smart with me, old love.'

Jericho was silent for a moment. He thought of the print of King's College Chapel with the intercepts hidden behind it. Of the German Book Room and Weitzman's frightened face. Of Edward Romilly's shaken voice. 'My daughter's movements are as much a mystery to me as they seem to be to you.' He was aware that Logie was studying him carefully.

'When does he want me to go?'

'Well, now, you bloody idiot. "Send him back to King's and this time letter the bugger walk" -1 seem to recall those were my specific instructions.' He sighed and shook his head. 'You shouldn't have made him look a fool, Tom. Not in front of his clients.'

'But he is a fool.' Outrage and self-pity were welling in him. He tried to keep his voice steady. 'He hasn't the foggiest idea of what he's talking about. Come on, Guy. Do you honestly believe, for one minute, that we can break back into Shark within the next three days?'

'No. But there are ways of saying it and there are ways of saying it, if you follow me, especially when our dearly beloved American brethren are in the same room.

Someone knocked and Logie shouted: 'Not now, old thing, thanks all the same!'

He waited until whoever it was had gone and then said, quietly: 'I don't think you quite appreciate how much things have changed round here.'

'That's what Skynner said.'

'Well, he's right. For once. You saw it for yourself at the conference yesterday. It's not 1940 any more, Tom. It's not plucky little Britain stands alone. We've moved on. We have to take account of what other people think. Just look at the map, man. Read the newspapers. These convoys embark from New York. A quarter of the ships are American. The cargo's all American. American troops. American crews.' Logie suddenly covered his face with his hands. 'My God, I can't believe you tried to hit Skynner. You really are pretty potty, aren't you? I'm not at all sure you're safe to walk the streets.' He lifted his feet off the desk and picked up the telephone. 'Look, I don't care what he says, I'll see if I can get the car to take you back.'

'No!' Jericho was surprised at the vehemence in his voice. In his mind he could see, perfectly replicated, the Atlantic plot – the brown landmass of North America, the Rorschach inkblots of the British Isles, the blue of the ocean, the innocent yellow discs, the shark's teeth, set and loaded like a mantrap. And Claire? Impossible to find her even now, when he had access to the Park. Shipped back to Cambridge, stripped of his security clearance, he might as well be on another planet. 'No,' he said, more calmly. 'You can't do that.'

'It's not my decision.'

'Give me a couple of days.'

'What?'

'Tell Skynner you want to give me a couple of days. Give me a couple of days to see if I can find a way back into Shark.'

Logie stared at Jericho for five seconds, then started to laugh. 'You get madder and madder as the week wears on, old son. Yesterday you're telling us Shark can't be broken in three days. Now you're saying you might be able to do it in two.'

'Please, Guy. I'm begging you.' And he was. He had his hands on Logie's desk and was leaning over it. He was pleading for his life. 'Skynner doesn't just want me out of the hut, you know. He wants me out of the Park altogether. He wants me locked up in some garret in the Admiralty doing long division.'

'There are worse places to spend the war.'

'Not for me there aren't. I'd hang myself. I belong here.'

'I have already stuck my neck out so far for you, my lad.' Logie jabbed his pipe into Jericho's chest.

'"Jericho?" they said. "You can't be serious. We're in a crisis and you want Jericho?" He jabbed his pipe again. 'So I said: "Yes, I know he's half bloody cracked and keeps on fainting like a maiden bloody aunt, but he's got something, got that extra two per cent. Just trust me."' Jab, jab. 'So I beg a bloody car – no joke round here, as you've gathered – and instead of getting my kip I come and drink stale tea in King's and plead with you, bloody plead, and the first thing you do is make us all look idiots and then you slug the head of section -all right, all right, try to slug him. Now, I ask you: who's going to listen to me now?'

'Skynner.'

'Come off it.'

'Skynner will have to listen, he will if you insist you need me. I know – ' Jericho was inspired. 'You could threaten to tell that admiral, Trowbridge, that I've been removed – at a vital moment in the Battle of the Atlantic – just because I spoke the truth.'

'Oh, I could, could I? Thank you. Thanks very much. Then we'll both be doing long division in the Admiralty.'

'"There are worse places to spend the war.'"

'Don't be cheap.'

There was another knock, much louder this time. 'For God's sake,' yelled Logie, 'piss off!' But the handle started to turn anyway. Jericho moved out of the way, the door opened and Puck appeared.

'Sorry, Guy. Good morning, Thomas.' He gave them each a grim nod. 'There's been a development, Guy.'

'Good news?'

'Frankly, no, to be entirely honest. It is probably not good news. You had better come.'

'Hell, hell muttered Logie. He gave Jericho a murderous look, grabbed his pipe and followed Puck out into the corridor.

Jericho hesitated for a second, then set off after them, down the passage and into the Registration Room. He had never seen it so full. Lieutenant Cave was there, along, it seemed, with almost every cryptanalyst in the hut – Baxter, Atwood, Pinker, Kingcome, Proudfoot, de Brooke – as well as Kramer, like a matinee idol in his American naval uniform. He gave Jericho a friendly nod.

Logie glanced around the room with surprise. 'Hail, hail, the gang's all here.' Nobody laughed. 'What's up, Puck? Holding a rally? Going on strike?'

Puck inclined his head towards the three young Wrens who made up the Registration Room's day shift.

'Ah yes,' said Logie, 'of course,' and he flashed his smoker's teeth at them in an ochre smile. 'Bit of business to attend to, girls. Hush hush. I wonder if you wouldn't mind leaving the gentlemen alone for a few minutes.'

'I happened to show this to Lieutenant Cave,' said Puck, when the Wrens had gone. 'Traffic analysis.' He held aloft the familiar yellow log sheet, as if he were about to perform a conjuring trick. 'Two long signals intercepted in the last twelve hours coming out of the Nazis' new transmitter near Magdeburg. One just before midnight: one hundred and eight four-letter groups. One just after: two hundred and eleven groups. Rebroadcast twice, over both the Diana and Hubertus radio nets. Four-six-oh-one kilocycles. Twelve-nine-fifty.'

'Oh, do get on with it,' said Atwood, under his breath.

Puck affected not to hear. 'In the same period, the total number of Shark signals intercepted from the North Atlantic U-boats up to oh-nine-hundred this morning: five.'

'Five?' repeated Logie. 'Are you sure, old love?' He took the log sheet and ran his finger down the neatly inked columns of entries.

'What's the phrase?' said Puck. "'As quiet as the grave"?'

'Our listening posts,' said Baxter, reading the log sheet over Logie's shoulder. 'There must be something wrong with them. They must have fallen asleep.'

'I rang the intercept control room ten minutes ago. After I'd spoken to the lieutenant. They say there's no mistake.'

An excited murmur of conversation broke out.

'And what say you, O wise one?'

It took Jericho a couple of seconds to realise that Atwood was talking to him. He shrugged. 'It's very few. Ominously few.'

Puck said: 'Lieutenant Cave believes there's a pattern.'

'We've been interrogating captured U-boat crew about tactics.' Lieutenant Cave leaned forwards and Jericho saw Pinker flinch at the sight of his scarred face. 'When Donitz sniffs a convoy, he draws his hearses up line abreast across the route he expects it to take. Twelve boats, say, maybe twenty miles apart. Possibly two lines, possibly three – nowadays he's got the hearses to put on a pretty big show. Our estimate, before the blackout, was forty-six operational in that sector of the North Atlantic alone.' He broke off, apologetically. 'Sorry,' he said, 'do stop me if I'm telling my grandmothers how to suck eggs.'

'Our work's rather more – ah – theoretical,' said Logie. He looked around and several of the crypt-analysts nodded in agreement.

'All right. There are basically two types of line. There's your picket line, which basically means the U-boats stay stationary on the surface waiting for the convoy to steam into them. And there's your patrol line, which involves the hearses sweeping forwards in formation to intercept it. Once the lines are established, there's one golden rule. Absolute radio silence until the convoy's sighted. My hunch is that that's what's happening now. The two long signals coming out of Magdeburg – those are most likely Berlin ordering the U-boats into line. And if the boats are now observing radio silence…' Cave shrugged: he was sorry to have to state the obvious. 'That means they must be on battle stations.'

Nobody said anything. The intellectual abstractions of cryptanalysis had taken solid form: two thousand German U-boat men, ten thousand Allied seamen and passengers, converging to do battle in the North Atlantic winter, a thousand miles from land. Pinker looked as if he might be sick. Suddenly the oddity of their situation struck Jericho. Pinker was probably personally responsible for sending – what? – a thousand German sailors to the bottom of the ocean, yet Cave's face was the closest he had come to the brutality of the Atlantic war.

Someone asked what would happen next.

'If one of the U-boats finds the convoy? It'll shadow it. Send a contact signal every two hours – position, speed, direction. That'll be picked up by the other hearses and they'll start to converge on the same location. Same procedure, to try to draw in as many hunters as possible. Usually, they try to get right inside the convoy, in among our ships. They'll wait until nightfall. They prefer to attack in the dark. Fires from the ships that have been hit illuminate other targets. There's more panic. Also, night-time makes it harder for our destroyers to catch them.'

'Of course, the weather's appalling,' added Cave, his sharp voice cutting in to the silence, 'even for the time of year. Snow. Freezing fog. Green water breaking over the bows. That's actually in our favour.'

Kramer said: 'How long do we have?'

'Less time than we originally thought, that's for certain. The U-boat is faster than any convoy, but it's still a slow beast. On the surface it moves at the speed of a man on a bicycle, underwater it's only as fast as a man on foot. But if Donitz knows about the convoys? Perhaps a day and a half. The bad weather will give them visibility problems. Even so – yes – I'd guess a day and a half at the outside.'

Cave excused himself to go and telephone the bad news to the Admiralty. The cryptanalysts were left alone. At the far end of the hut a faint clacking noise began as the Type-X machines started their day's work.

'That'll be D-D-Dolphin,' said Pinker. 'Will you excuse me, G-G-Guy?'

Logie raised a hand in benediction and Pinker hurried out of the room.

'If only we had a four-wheel bombe,' moaned Proudfoot.

'Well, we ain't got one, old love, so don't let's waste time on that.'

Kramer had been leaning against one of the trestle tables. Now he pushed himself on to his feet. There wasn't room for him to pace, so he performed a kind of restless shuffle, smacking his fist into the palm of his left hand.

'Goddamn it, I feel so helpless. A day and a half. A measly, goddamn day and a half jesus! There must be something. I mean, you guys did break this thing once, didn't you, during the last blackout?'

Several people spoke at once.

'Oh, yes.'

'D'you remember that?'

'That was Tom.'

Jericho wasn't listening. Something was stirring in his mind, some tiny shift in the depths of his subconscious, beyond the reach of any power analysis. What was it? A memory? A connection? The more he tried to concentrate on it, the more elusive it became.

'Tom?'

He jerked his head up in surprise.

'Lieutenant Kramer was asking you, Tom' said Logie, with weary patience, 'about how we broke Shark during the blackout.'

'What?' He was irritated at having his thoughts interrupted. His hands fluttered. 'Oh, Donitz was promoted to admiral. We took a guess that U-boat headquarters would be pleased as Punch. So pleased, they'd transmit Hitler's proclamation verbatim to all boats.'

'And did they?'

'Yes. It was a good crib. We put six bombes onto it. Even then it still took us nearly three weeks to read one day's traffic.'

'With a good crib?' said Kramer. 'Six bombes. Three weeks?'

'That's the effect of a four-wheel Enigma.'

Kingcome said: 'It's a pity Donitz doesn't get a promotion every day.'

This immediately brought Atwood to life. 'The way things are going, he probably will.'

Laughter momentarily lightened the gloom. Atwood looked pleased with himself.

'Very good, Frank,' said Kingcome. 'A daily promotion. Very good.'

Only Kramer refused to laugh. He folded his arms and stared down at his gleaming shoes.

They began to talk about some theory of de Brooke's which had been running on a pair of bombes for the past nine hours, but the methodology was hopelessly skewed, as Puck pointed out.

'Well, at least I've had an idea,' said de Brooke, 'which is more than you have.'

'That is because, my dear Arthur, if I have a terrible idea, I keep it to myself.'

Logie clapped his hands. 'Boys, boys. Let's keep the criticism constructive, shall we?'

The conversation dragged on but Jericho had stopped listening a long time ago. He was chasing the phantom in his mind again, searching back through his mental record of the past ten minutes to find the word, the phrase, that could have stirred it into life. Diana, Hubertus, Magdeburg, picket line, radio silence, contact signal…

Contact signal.

'Guy, where d'you keep the keys to the Black Museum?'

'What, old thing? Oh, in my desk. Top right-hand drawer. Hey, where're you going? Just a minute, I haven't finished talking to you yet…'

It was a relief to get out of the claustrophobic atmosphere of the hut and into the cold, fresh air. He trotted up the slope towards the mansion.

He seldom went into the big house these days but whenever he did it reminded him of a stately home in a twenties murder mystery. (' You will recall, inspector, that the colonel was in the library when the fatal shots were fired…') The exterior was a nightmare, as if a giant handcart full of the discarded bits of other buildings had been tipped out in a heap. Swiss gables, Gothic battlements, Greek pillars, suburban bay windows, municipal red brick, stone lions, the entrance porch of a cathedral – the styles sulked and raged against one another, capped by a bell-shaped roof of beaten green copper. The interior was pure Gothic horror, all stone arches and stained glass windows. The polished floors rang hollow beneath Jericho's feet and the walls were decorated with dark wooden panelling of the sort that springs open in the final chapter to reveal a secret labyrinth. He was hazy about what went on here now. Commander Travis had the big office at the front looking out over the lake while upstairs in the bedrooms all sorts of mysterious things were done: he'd heard rumours they were breaking the ciphers of the German Secret Service.

He walked quickly across the hall. An Army captain loitering outside Travis's office was pretending to read that morning's Observer, listening to a middle-aged man in tweeds trying to chat up a young RAF woman. Nobody paid any attention to Jericho. At the foot of the elaborately carved oak staircase, a corridor led off to the right and wound around the back of the house. Midway along it was a door which opened to reveal steps down to a secondary passage. It was here, in a locked room in the cellar, that the cryptanalysts from huts 6 and 8 stored their stolen treasures.

Jericho felt along the wall for the light switch.

The larger of the two keys unlocked the door to the museum. Stacked on metal shelves along one wall were a dozen or more captured Enigma machines. The smaller key fitted one of a pair of big iron safes. Jericho knelt and opened it and began to rummage through the contents. Here they all were, their precious pinches: each one a victory in the long war against the Enigma. There was a cigar box with a label dated February 1941, containing the haul from the armed German trawler Krebs: two spare rotors, the Kriegsmarine grid map of the North Atlantic and the naval Enigma settings for February 1941. Behind these was a bulging envelope marked Munchen – a weather ship whose capture three months after the Krebs had enabled them to break the meterological code – and another labelled 'U-110'. He pulled out armfuls of papers and charts.

Finally, from the bottom shelf at the back, he withdrew a small package wrapped in brown oilcloth. This was the haul for which Fasson and Grazier had died, still in its original covering, as it had been passed out of the sinking U-boat. He never saw it without thanking God that they'd found something waterproof to wrap it in. The smallest exposure to water would have dissolved the ink. To have plucked it from a drowning submarine, at night, in a high sea… It was enough to make even a mathematician believe in miracles. Jericho removed the oilcloth tenderly, as a scholar might unwrap the papyri of an ancient civilisation, or a priest uncover holy relics. Two little pamphlets, printed in Gothic lettering on pink blotting paper. The second edition of the U-boats' Short Weather Cipher, now useless, thanks to the code book change. And – exactly as he had remembered – the Short Signal Book. He flicked through it. Columns of letters and numbers.

A typed notice was stuck on the back of the safe door: 'It is strictly forbidden to remove any item without my express permission. (Signed) L.F.N. Skynner, Head of Naval Section.'

Jericho took particular pleasure in slipping the Short Signal Book into his inside pocket and running with it back to the hut.

Jericho tossed the keys to Logie who fumbled and then just caught them.

'Contact signal.'

'What?'

'Contact signal,' repeated Jericho.

'Praise the Lord!' said Atwood, throwing up his hands like a revivalist preacher. 'The Oracle has spoken.'

'All right, Frank. Just a minute. What about it, old love?'

Jericho could see it all much faster than he could convey it. Indeed, it was quite hard to formulate it in words at all. He spoke slowly, as if translating from a foreign language, reordering it in his mind, turning it into a narrative.

'Do you remember, in November, when we got the Short Weather Cipher Book off the U-459? When we also got the Short Signal Book? Only we decided not to concentrate on the Short Signal Book at the time, because it never yielded anything long enough to make a worthwhile crib? I mean, a convoy contact signal on its own, it isn't worth a damn, is it? It's just five letters once in a blue moon.' Jericho withdrew the little pink pamphlet carefully from his pocket. 'One letter for the speed of the convoy, a couple for its course, a couple more for the grid reference

Baxter stared at the code book as if hypnotised. 'You've removed that from the safe without permission?

'But if Lieutenant Cave is correct, and whichever U-boat finds the convoy is going to send a contact signal every two hours, and if it's going to shadow it till nightfall, then it's possible – theoretically possible – it might send as many as four, or even five signals, depending on what time of day it makes its first sighting.' Jericho sought out the only uniform in the room. 'How long does daylight last in the North Atlantic in March?'

'About twelve hours,' said Kramer.

'Twelve hours, you see? And if a number of other U-boats attach themselves to the same convoy, on the same day, in response to the original signal, and they all start sending contact signals every two hours

Logie, at least, could see what he was driving at. He withdrew his pipe slowly from his mouth. 'Bloody hell!'

'Then again, theoretically, we could have, say, twenty letters of crib off the first boat, fifteen off the second – I don't know, if it's an attack by eight boats, let's say, we could easily get to a hundred letters. It's just as good as the weather crib.' Jericho felt as a proud as a father, offering the world a glimpse of his newborn child. 'It's beautiful, don't you see?' He gazed at each of the crytanalysts in turn: Kingcome and Logie were begin-to look excited, de Brooke and Proudfoot seemed thoughtful, Baxter, Atwood and Puck appeared down-right hostile. 'It was never possible till this moment, because until now the Germans have never been able to throw so many U-boats against such a mass of shipping. It's the whole story of Enigma in a nutshell. The very scale of the Germans' achievement breeds such a mass of malrial for us, it'll sow the seeds of their eventual defeat.'

He paused.

Aren't there rather a lot of ifs there?' said Baxter drily. 'If the U-boat finds the convoy early enough in the day, if it reports every two hours, if the others all do the same, manage to intercept every transmission…'

'And if' said Atwood, 'the Short Signal Book we pinched in November wasn't changed last week at the same time as the Weather Cipher Book

That was a possibility Jericho hadn't considered. He felt his enthusiasm crumble slightly.

Now Puck joined in the attack. 'I agree. The concept is quite brilliant, Thomas. I applaud your – inspiration, I suppose. But your strategy depends on failure, does it not We will only break Shark, on your admission, if the U-Boats find the convoy, which is exactly what we want to avoid. And suppose we do come up with that day's Shark settings – so what? Marvellous. We can read all the U-boats' signals to Berlin, boasting to Donitz about how many Allied ships they've sunk. And twenty-four hours later, we're blacked out again.'

Several of the cryptanalysts groaned in agreement.

'No, no,' Jericho shook his head emphatically. 'Your logic is flawed, Puck. What we hope, obviously, is that the U-boats don't find the convoys. Yes – that's the whole point of the exercise. But if they do, we can at least turn it to our advantage. And it won't just be one day, not if we're lucky. If we break the Shark settings for twenty-four hours, then we'll pick up the encoded weather messages for that entire period. And, remember, we'll have our own ships in the area, able to give us the precise weather data the U-boats are encoding. We'll have the plaintext, we'll have the Shark cipher settings, so we'll be able to make a start on reconstructing the new Weather Code Book. We could get our foot back in the door again. Don't you see?'

He ran his hands through his hair and tugged at it in exasperation. Why were they all being so dim?

Kramer had been scribbling furiously in a notebook. 'He's on to something, you know.' He tossed his pencil into the air and caught it. 'Come on. It's worth a try. At least it puts us back in the fight.'

Baxter grunted. 'I still don't see it.'

'Nor do I,' said Puck.

'I suppose you don't see it, Baxter,' said Atwood, 'because it doesn't represent a triumph for the world proletariat?'

Baxter's hands curled into fists. 'One of these days, Atwood, someone's going to knock your bloody smug block off.'

'Ah. The first impulse of the totalitarian mind: violence.'

'Enough!' Logie banged his pipe like a gavel on one of the trestle tables. None of them had ever heard him shout before and the room went quiet. 'We've had quite enough of that already.' He stared hard at Jericho. 'Now, it's quite right we should be cautious. Puck, your point's taken. But we've also got to face facts. We've been blacked out four days and Tom's is the only decent idea we've got. So bloody good work, Tom.'

Jericho stared at an ink stain on the floor. Oh God, he thought, here comes the housemaster's pep talk.

'Now, there's a lot resting on us here, and I want every man to remember he's part of a team.'

'No man is an island, Guy,' said Atwood, deadpan, his chubby hands clasped piously on his wide stomach.

'Thank you, Frank. Quite right. No they're not. And if ever any of us – any of us – is tempted to forget it, just think of those convoys, and all the other convoys this war depends on. Got it? Good. Right. Enough said. Back to work.'

Baxter opened his mouth to protest, but then seemed to think better of it. He and Puck exchanged grim glances on their way out. Jericho watched them go and wondered why they were so determinedly pessimistic. Puck couldn't abide Baxter's politics and normally the two men kept their distance. But now they seemed to have made common cause. What was it? A kind of academic jealousy? Resentment that he had come in after all their hard work and made them look like fools?

Logie was shaking his head. 'I don't know, old love, what are we to do with you?' He tried to look stern, but he couldn't hide his pleasure. He put his hand on Jericho's shoulder.

'Give me my job back.'

'I'll have to talk to Skynner.' He held the door open and ushered Jericho out into the passage. The three Wrens watched them. 'My God,' said Logie, with a shudder. 'Can you imagine what he's going to say? He's going to love it, isn't he, having to tell his friends the admirals that the best chance of getting back into Shark is if the convoys are attacked? Oh, bugger, I suppose I'd better go and call him.' He went halfway into his office, then came out again. 'And you're quite sure you never actually hit him?'

'Quite sure, Guy.'

'Not a scratch?'

'Not a scratch.'

'Pity, said Logie, half to himself. 'In a way. Pity.'

5

Hester Wallace couldn't sleep. The blackout curtains were drawn against the day. Her tiny room was a study in monochrome. A nosegay of lavender sent a soothing fragrance filtering through her pillow. But even though she lay dutifully on her back in her cotton nightgown, her legs pressed together, her hands folded on her breast, like a maiden on a marble tomb, oblivion still eluded her.

'ADU, Miss Wallace. Angels Dance Upwards

The mnemonic was infuriatingly effective. She couldn't get it out of her brain, even though the arrangement of letters meant nothing to her.

'It's a call sign. Probably German Army or Luftwaffe…"

No surprise in that. It was almost bound to be. After all, there were so many of them: thousands upon thousands. The only reliable rule was that Army and Luftwaffe call-signs never began with a D, because D always indicated a German commercial station.

ADU…ADU…

She couldn't place it.

She turned on her side, brought her knees up to her stomach and tried to fill her mind with soothing thoughts. But no sooner had she rid herself of the intense, pale face of Tom Jericho than her memory showed her the wizened priest of St Mary's, Bletchley, that croaking mouthpiece of St Paul's misogynies. 'It is a shame for women to speak in the church…' (1 Corinthians I4.xxxv). 'Silly women laden with sins, led away with divers lusts…' (2 Timothy 3.vi). From such texts he had woven a polemical sermon against the wartime employment of the female sex – women driving lorries, women in trousers, women drinking and smoking in public houses unaccompanied by their husbands, women neglecting their children and their homes. 'As a jewel of gold in a swine's mouth, so is a fair woman which is without discretion.' (Proverbs ll.xxii).

If only it were true! she thought. If only women had usurped authority over men! The Brylcreemed figure of Miles Mermagen, her head of section, rose greasily before her inner eye. 'My dear Hester, a transfer at the present moment is really quite out of the question.' He had been a manager at Barclays Bank before the war and liked to come up behind the girls as they worked and massage their shoulders. At the Hut 6 Christmas Party he had manoeuvred her under the mistletoe and clumsily taken off her glasses. ('Thank you, Miles,' she'd said, trying miserably to make a joke of it, 'without my spectacles you too look almost tolerably attractive…') His lips on hers were unpleasantly moist, like the underside of a mollusc, and tasted of sweet sherry.

Claire, of course, had known immediately what to do.

'Oh, darling, poor you, and I suppose he's got a wife?'

'He says they were married too young.'

'Well, she's your answer. Tell him you think it's only fair you go and have a talk with her first. Tell him you want to be her friend.'

'But what if he says yes?'

'Oh, God! Then I suppose you'll just have to kick him in the balls.'

Hester smiled at the memory. She shifted her position in the bed again and the cotton sheet rode up and corrugated beneath her. It was quite hopeless. She reached out and switched on the little bedside lamp, fumbling around its base for her glasses.

Ich lerne deutsch, ich lernte deutsch, ich habe deutsch gelernt…

German, she thought: German would be her salvation. A working knowledge of written German would lift her out of the grind of the Intercept Control Room, away from the clammy embrace of Miles Mermagen, and propel her into the rarefied air of the Machine Room, where the real work was done – where she should have been put in the first place.

She propped herself up in bed and tried to focus on Abelman's German Primer. Ten minutes of this was usually quite enough to send her off to sleep.

'Intransitive verbs showing a change of place or condition take the auxiliary sein instead of haben in the compound tenses

She looked up. Was that a noise downstairs?

'In subordinate word order the auxiliary must stand last, directly after the past participle or the infinitive

And there it was again.

She slipped her warm feet into her cold outdoor shoes, wrapped a woollen shawl about her shoulders, and went out onto the landing.

A knocking sound was coming from the kitchen.

She began to descend the stairs.

There had been two men waiting for her when she arrived back from church. One had been standing on the doorstep, the other had emerged casually from the back of the cottage. The first man was young and blond with a languid, aristocratic manner and a kind of decadent Anglo-Saxon handsomeness. His companion was older, smaller, slim and dark, with a northern accent. They both had Bletchley Park passes and said they'd come from Welfare and were looking for Miss Romilly. She hadn't turned up for work: any idea where she might be?

Hester had said she hadn't. The older man had gone upstairs and had spent a long time searching around. The blond, meanwhile – she never caught his name -had sprawled on the sofa and asked a lot of questions. There was something offensively patronising about him, for all his good manners. This is what Miles Mermagen would be like, she found herself thinking, if he'd had five thousand pounds' worth of private education. What was Claire like? Who were her friends? Who were the men in her life? Had anyone been asking after her? She mentioned Jericho's visit of the previous night and he made a note of it with a gold propelling pencil. She almost blurted out the story of Jericho's peculiar approach in the churchyard ('ADU, Miss Wallace…') but by this time she had taken so strongly against the blond man's manner she bit back the words.

Knock, knock, knock from the kitchen…

Hester took the poker that stood beside the sitting-room fireplace and slowly opened the kitchen door.

It was like stepping into a refrigerator. The window was banging in the wind. It must have been open for hours.

At first she felt relieved, but that lasted only until she tried to close it. Then she discovered that the metal catch, weakened by rust, had been snapped clean off. Part of the wooden window frame around it was splintered.

She stood in the cold and considered the implications and quickly concluded there was only one plausible explanation. The dark-haired man who had appeared from behind the cottage on her return from church had obviously been in the process of breaking in.

They had told her there was nothing to worry about. But if there was nothing to worry about, why had they been prepared to force entry into the house?

She shivered and drew the shawl around her.

'Oh Claire,' she said aloud, 'oh, Claire, you silly, stupid, stupid girl, what have you done?'

She used a piece of blackout tape to try and secure the window. Then, still holding the poker, she went back upstairs and into Claire's room. A silver fox was hanging over the end of the bed, its glass-bead eyes staring, its needle teeth bared. Out of habit, she folded it neatly and placed it on the shelf where it normally lived. The room was such an expression of Claire, such an extravagance of colour and fabric and scent, that it seemed to resonate with her presence, even now, when she was away, to hum with it, like the last vibrations of a tuning fork… Claire, holding some ridiculous dress to herself and laughing and asking her what she thought, and Hester pretending to frown with an older sister's disapproval. Claire, as moody as an adolescent, on her stomach on the bed, leafing through a pre-war Tatler. Claire combing Hester's hair (which, when she let it down, fell almost to her waist), running her brush through it with slow and languorous strokes that made Hester's limbs turn weak. Claire insisting on painting Hester in her make-up, dressing her up like a doll and standing back in mock surprise: 'Why, darling, you're beautiful! Claire, in nothing but a pair of white silk knickers and a string of pearls, prancing about the room in search of something, long-legged as an athlete, turning and seeing that Hester was secretly watching her in the mirror, catching the look in her eyes, and standing there for a moment, hip thrust forward, arms outstretched, with a smile that was something between an invitation and a taunt, before sweeping back into motion…

And on that cold, bright Sabbath afternoon, Hester Wallace, the clergyman's daughter, leaned against the wall and closed her eyes and pressed her hand between her legs with shame.

An instant later the noise from the kitchen started again and she thought her heart might burst with panic. She fled across the landing and into her room, pursued by the dry whine of the vicar of St Mary's – or was it really the voice of her father? – reciting from the Book of Proverbs:

'For the lips of a strange woman drop as an honeycomb, and her mouth is smoother than oil: But her end is bitter as wormwood, sharp as a two-edged sword. Her feet go down to death; her steps take hold on hell…'

6

For the first time in more than a month, Tom Jericho found that he was busy.

He had to supervise the copying of the Short Signal Code Book, six typewritten transcripts of which were duly produced and stamped MOST SECRET. Every line had to be checked, for a single error could spell the difference between a successful break and days of failure. The intercept controllers had to be briefed. Teleprintered orders had to be sent to all the duty officers of every Hut 8 listening post – from Thurso, clinging to the cliffs on the northernmost tip of Scotland, right down to St Erth, near Land's End. Their brief was simple: concentrate everything you have on the known Atlantic U-boat frequencies, cancel all leave, bring in the lame and the sick and the blind if you have to, and pay even greater attention than usual to very short bursts of Morse preceded by E-bar – dot dot dash dot dot – the Germans' priority code which cleared the wavelength for convoy contact reports. Not one such signal was to be missed, understand? Not one.

From the Registry, Jericho withdrew three months' worth of Shark decrypts to bring himself back up to speed, and, that afternoon, sitting in his old place by the window in the Big Room, proved by slide-rule calculation what he already knew by instinct: that seventeen convoy contact reports, if harvested in the same twenty-four-hour stretch, would yield eighty-five letters of cipher encode which might – might, if the cryptanalysts had the requisite percentage of luck- give them a break into Shark, provided they could get at least ten bombes working in relay for a minimum of thirty-six hours…

And all the time he thought of Claire.

There was very little, practically, he could do about her. Twice during the day he managed to get out to the telephone box to try to call her father: once as they all went off to lunch, when he was able to drop back, unnoticed by the rest, just before they reached the main gate; and the second time in the late afternoon when he pretended he needed to stretch his legs. On each occasion, the connection was made, but the phone merely rang, unanswered. He had a vague but growing feeling of dread, made worse by his powerlessness. He couldn't return to Hut 3. He didn't have the time to check out her cottage. He would have liked to go back to his room to rescue the intercepts -hidden behind a picture on top of the mantelpiece'', was he insane? – but the round trip would have taken him the best part of twenty minutes and he couldn't get away.

In the event, it was to be well past seven before he got away. Logie was passing through the Big Room when he stopped off at Jericho's table and told him, for God's sake, to get back to his digs and get some rest. 'There's nothing more for you to do here, old love. Except wait. I expect it'll be around this time tomorrow that we'll start to sweat.'

Jericho reached thankfully for his coat. 'Did you talk to Skynner?'

'About the plan, yes. Not about you. He didn't ask and I certainly wasn't going to bring it up.'

'Don't tell me he's forgotten?'

Logie shrugged. 'There's some other flap on that seems to have taken his mind off things.'

'What other flap?'

But Logie had moved away. 'I'll see you in the morning. You just make sure you get some kip.'

Jericho returned the stack of Shark intercepts to the Registry and went outside. The March sun, which had barely risen above the trees all day, had sunk behind the mansion, leaving a fading streak of primrose and pale orange at the rim of an indigo sky. The moon was already out and Jericho could hear the sound of bombers, far away, a lot of them, forming up for the night's attack on Germany. As he walked, he gazed around him in wonder. The lunar disc on the still lake, the fire on the horizon – it was an extraordinary conjunction of lights and symbols, almost like a portent. He was so engrossed he had almost passed the telephone box before he realised that it was empty. One last try? He glanced at the moon. Why not? The Kensington number still wasn't answering so he decided, on a whim, to try the Foreign Office. The operator put him through to a duty clerk and he asked for Edward Romilly. 'Which department?' 'I don't know, I'm afraid.'

The line went silent. The chances of Edward Romilly being at his desk on a Sunday night were slim. He rested his shoulder against the glass panel of the booth. A car went past slowly, then pulled up about ten yards down the road. Its brake lights glowed red in the dusk. There was a click and Jericho returned his attention to the call. 'Putting you through.'

A ringing tone, and then a cultured female voice said: 'German Desk.'

German Desk? He was momentarily disconcerted. 'Ah, Edward Romilly, please.'

'And who shall I say is calling?'

My God, he was there. He hesitated again.

'A friend of his daughter.'

'Wait, please.'

His fingers were clamped so tight around the receiver that they were aching. He made an effort to relax. There was no good reason why Romilly shouldn't work on the German Desk. Hadn't Claire told him once that her father had been a junior official at the Berlin Embassy, just as the Nazis were coming to power? She would have been about ten or eleven. That must have been where she learned her German.

'I'm afraid, sir, Mr Romilly's already left for the evening. Who shall I say called?'

'Thank you. It doesn't matter. Good night.'

He hung up quickly. He didn't like the sound of that. And he didn't like the look of this car, either. He came out of the telephone box and began to walk towards it – a low, black machine with wide running boards, edged white for the blackout. Its engine was still running. As he came closer it suddenly catapulted forwards and shot round the curving road towards the main gate. He trotted after it but by the time he reached the entrance it had gone.

As Jericho went down the hill, the vague outline of the town evaporated into the darkness. No generation for at least a century could have witnessed such a spectacle. Even in his great-grandfather's day there would have been some illumination – the gleam of a gaslight or a carriage lantern, the bluish glow of a night watchman's paraffin lamp – but not any more. As the light faded, so did Bletchley. It seemed to sink into a black lake. He could have been anywhere.

He was aware, now, of a certain paranoia, and the night magnified his fears. He passed an urban pub close to the railway bridge, an elaborate Victorian mausoleum with FINE WHISKYS, PORTS AND STOUTS inlaid in gold on the black masonry like an epitaph. He could hear a badly tuned piano playing 'The Londonderry Air' and for a moment he was tempted to go in, buy a drink, find someone to talk to. But then he imagined the conversation -

'So, what's your line then, pal?'

'Just government work.'

'Civil service?'

'Communications. Nothing much. Look, I say, can I get you another drink?'

'Local are you?'

'Not exactly…'

– and he thought: no, better to keep clear of strangers; best, really, not to drink at all. As he was turning into Albion Street he heard the scrape of a footstep behind him and spun round. The pub door had opened, there was a moment of colour and music, then it closed and the road was dark again.

The guesthouse was about half way down Albion Street, on the right and he had almost reached it when he noticed, on the left, a car. He slowed his pace. He couldn't be sure it was the same one that had behaved so oddly at the Park, although it looked quite similar. But then, when he was almost level with it, one of the occupants struck a match. As the driver leaned over to cup his hand to the light, Jericho saw on his sleeve the three white stripes of a police sergeant.

He let himself into the guesthouse and prayed he could make the stairs before Mrs Armstrong rose like a night fighter to intercept him in the hall. But he was too late. She must have been waiting for the sound of his key in the latch. She appeared from the kitchen through a cloud of steam that smelled of cabbage and offal. In the dining room, somebody made a retching noise and there was a shout of laughter.

Jericho said weakly, 'I don't think I'm very hungry, Mrs Armstrong, thanks all the same.'

She dried her hands on her apron and nodded towards a closed door. 'You've got a visitor.'

He had just planted his foot defiantly on the first stair. 'Is it the police?'

'Why, Mr Jericho, whatever would the police be doing here? It's a very nice-looking young gentleman. I've put him,' she added, with heavy significance, 'in the parlour.'

The parlour! Open nightly to any resident from eight till ten on weekdays, and from teatime onwards, Saturday and Sunday: as formal as a ducal drawing room, with its matching three-piece suite and antimacassars (made by the proprietress herself), its mahogany standard lamp with tasselled shade, its row of grinning Toby jugs, precisely lined above its freezing hearth. Who had come to see him, wondered Jericho, who warranted admission to the parlour?

At first he didn't recognise him. Golden hair, a pale and freckled face, pale blue eyes, a practised smile. Advancing across the room to meet him, right hand outstretched, left hand holding an Anthony Eden hat, fifty guineas' worth of Savile Row coat draped over manly shoulders. A blur of breeding, charm and menace.

'Wigram. Douglas Wigram. Foreign Office. We met yesterday but weren't introduced properly.'

He took Jericho's hand lightly and oddly, a finger crooked back into his palm, and it took Jericho a moment to realise he had just been the recipient of a masonic handshake.

'Digs all right? Super room, this. Super. Mind if we go somewhere else? Whereabouts are you based? Upstairs?'

Mrs Armstrong was still in the hall, fluffing up her hair in front of the oval mirror.

'Mr Jericho suggests we might have our little chat upstairs in his room, if that's OK with you, Mrs A?' He didn't wait for a reply. 'Let's go then, shall we?'

He held out his arm, still smiling, and Jericho found himself being ushered up the stairs. He felt as though he had been tricked or robbed but he couldn't work out how. On the landing he rallied sufficiently to turn and say, 'It's very small, you know, there's barely room to sit.'

'That's perfectly all right, my dear chap. As long as it's private. Onwards and upwards.'

Jericho switched on the dim light and stood back to let Wigram go in first. There was a faint whiff of eau de cologne and cigars as he brushed past. Jericho's eyes went straight to the picture of the chapel, which, he was relieved to note, looked undisturbed. He closed the door.

'See what you mean about the room,' said Wigram, cupping his hands to the glass to peer out of the window. 'The hell we have to go through, what? And a railway view thrown in. Bliss.' He closed the curtains and turned back to Jericho. He was cleaning his fingers on a handkerchief with almost feminine delicacy. 'We're rather worried.' His smile widened. 'We're rather worried about a girl called Claire Romilly.' He folded the blue silk square and thrust it back into his breast pocket. 'Mind if I sit down?'

He shrugged off his overcoat and laid it on the bed, then hitched up his pinstriped trousers a fraction at the knees to avoid damaging the crease. He sat on the edge of the mattress and bounced up and down experimentally. His hair was blond; so were his eyebrows, his eyelashes, the hairs on the back of his neat white hands… Jericho felt his skin prickle with fear and disgust.

Wigram patted the eiderdown beside him. 'Let's talk.' He didn't seem the least put out when Jericho stayed where he was. He merely folded his hands contentedly in his lap.

'All right,' he said, 'we'll make a start, then, shall we? Claire Romilly. Twenty. Clerical grade staff. Officially missing for -' he looked at his watch '- twelve hours. Failed to show for her morning shift. Actually, when you start to check, not seen since midnight, Friday – dear oh dear, that's nearly two days ago now – when she left the Park after work. Alone. The girl she lives with swears she hasn't seen her since Thursday. Her father says he hasn't seen her since before Christmas. Nobody else – girls she works with, family, so forth – nobody seems to have the foggiest. Vanished.' Wigram snapped his fingers. 'Just like that.' For the first time he'd stopped smiling. 'Rather a good friend of yours, I gather?'

'I haven't seen her since the beginning of February. Is this why there are police outside?'

'But good enough? Good enough that you've tried to see her? Out to her cottage last night, according to our little Miss Wallace. Scurry, scurry. Questions, questions. Then, this morning, into Hut 3 – questions, questions, again. Phone call to her father – oh, yes,' he said, noticing Jericho's surprise, 'he rang us straight away to say you'd called. You've never met Ed Romilly? Lovely bloke. Never achieved his full potential, so they say. Rather lost the plot after his wife died. Tell me, Mr Jericho, why the interest?'

'I'd been away for a month. I hadn't seen her.'

'But surely you've got plenty more important things to worry about, especially just now, than renewing one acquaintance?'

His last words were almost lost in the roar of a passing express train. The room vibrated for fifteen seconds, which was the exact duration of his smile. When the noise was over, he said: 'Were you surprised to be brought back from Cambridge?'

'Yes. I suppose I was. Look, Mr Wigram, who are you, exactly?'

'Surprised when you were told why you were needed back?'

'Not surprised. No.' He searched for the word. 'Shocked.'

'Shocked. Ever talk to the girl about your work?'

'Of course not.'

'Of course not. Strike you as odd, though – possibly more than a coincidence, possibly even sinister – that one day the Germans black us out in the North Atlantic and two days later the girlfriend of a leading Hut 8 cryptanalyst goes missing? Actually on the same day he comes back?'

Jericho's gaze flickered involuntarily to the print of the chapel. 'I told you. I never talked to Claire about my work. I hadn't seen her for a month. And she wasn't my girlfriend.'

'No? What was she then?'

What was she then? A. good question. 'I just wanted to see her,' he said lamely. 'I couldn't find her. I was concerned.'

'Got a photo of her? Something recent?'

'No. Actually, I don't have any pictures of her.'

'Really? Now here's another funny thing. Pretty girl like that. But can we find a picture? We'll just have to use the ID copy from her Welfare file.'

'Use it for what?'

'Can you fire a gun, Mr Jericho?'

'I couldn't hit a duck at a funfair.'

'Now that's what I would have thought, though one shouldn't always judge a chap by his looks. Only the Bletchley Park Home Guard had a little burglary at their armoury on Friday night. Two items missing. A Smith and Wesson.38 revolver, manufactured in Springfield, Massachusetts, issued by the War Office last year. And a box containing thirty-six rounds of ammunition.'

Jericho said nothing. Wigram looked at him for a while, as if he were making up his mind about something. 'No reason why you shouldn't know, I suppose. Trustworthy fellow like you. Come and sit down.' He patted the eiderdown again. 'I can't keep shouting the biggest frigging secret in the British Empire across your frigging bedroom. Come on. I won't bite, I promise.'

Reluctantly, Jericho sat down. Wigram leaned forwards. As he did so, his jacket parted slightly, and Jericho glimpsed a flash of leather and gunmetal against the white shirt.

'You want to know who I am?' he said softly. 'I'll tell you who I am. I'm the man our masters have decreed should find out just what's what down here in your little anus mundi.' He was speaking so quietly, Jericho was obliged to move his head in close to hear. 'Bells are going off, you see. Horrible, horrible bells. Five days ago, Hut 6 decoded a German Army signal from the Middle East. General Rommel's becoming a bit of a bad sport. Seems to think the only reason he's losing is that somehow, by some miracle, we always appear to know where exactly he's going to attack. Suddenly, the Afrika Korps want an enquiry into cipher security. Oh dear. Ding dong. Twelve hours later, Admiral Donitz, for reasons as yet unknown, suddenly decides to tighten Enigma procedure by changing the U-boat weather code. Ding dong again. Today, it's the Luftwaffe. Four German merchant ships loaded with goodies for the aforementioned Rommel were recently "surprised" by the RAF and sunk halfway to Tunisia. This morning, we read that the German C-in-C, Mediterranean, Field Marshal Kesselring himself, no less, is demanding to know whether the enemy could have read his codes.' Wigram patted Jericho's knee. 'Peals of alarms, Mr Jericho. A Westminster-Abbey-on-Coronation-Day peal of alarms. And in the middle of them all, your lady friend disappears, at the same time as a shiny new shooter and a box of bullets.'

'Exactly who or what are we dealing with here?' said Wigram. He had taken out a small black leather notebook and a gold propelling pencil. 'Claire Alexandra Romilly. Born: London, twenty-first of the twelfth, 'twenty-two. Father: Edward Arthur Macauley Romilly, diplomat. Mother: the Honourable Alexandra Romilly, nee Harvey, deceased in motor accident, Scotland, August 'twenty-nine. The child is educated privately abroad. Father's postings: Bucharest, 'twenty-eight to 'thirty-one; Berlin, 'thirty-one to 'thirty-four; Washington, 'thirty-four to 'thirty-eight. A year in Athens, then back to London. The girl by now is at some fancy finishing school in Geneva. She returns to London on the outbreak of war, aged seventeen. Principal occupation for the next three years, as far as one can gather: having a good time.' Wigram licked his finger and turned the page. 'Some voluntary civil defence work. Nothing too arduous. July 'forty-one: translator at the Ministry of Economic Warfare. August 'forty-two: applies for clerical position, Foreign Office. Good languages. Recommended for position at Bletchley Park. See attached letter from father, blah, blah. Interviewed 10th of September. Accepted, cleared, starts work the following week.' Wigram flicked the pages back and forth. 'That's the lot. Not exactly a rigorous process of selection, is it? But then she does come from a frightfully good family. And Papa does work down at head office. And there is a war on. Care to add anything to the record?'

'I don't think I can.'

'How'd you meet her?'

For the next ten minutes Jericho answered Wigram's questions. He did this carefully and – mostly -truthfully. Where he lied it was only by omission. They had gone to a concert for their first date. After that they had gone out in the evenings a few times. They had seen a picture. Which one? In Which We Serve.

'Like it?'

'Yes.'

'I'll tell Noel.'

She had never talked about politics. She had never discussed her work. She had never mentioned other friends.

'Did you sleep with her?'

'Mind your own bloody business.'

'I'll put that down as yes.'

More questions. No, he had noticed nothing odd about her behaviour. No, she had not seemed tense or nervous, secretive, silent, aggressive, inquisitive, moody, depressed or elated – no, none of these – and at the end, they hadn't quarrelled. Really? No. So they had… what, then?

'I don't know. Drifted apart.'

'She was seeing someone else?'

'Perhaps. I don't know.'

'Perhaps. You don't know.' Wigram shook his head in wonder. 'Tell me about last night.'

'I cycled over to her cottage.'

'What time?'

'About ten, ten-thirty. She wasn't there. I talked with Miss Wallace for a bit. Then I came home.'

'Mrs Armstrong says she didn't hear you come in until around two o'clock this morning.'

So much for tiptoeing past her door, thought Jericho.

'I must have cycled around for a while.'

'I'll say you did. In the frost. In the blackout. You must have cycled around for about three hours.'

Wigram gazed down at his notes, tapping the side of his nose. 'Not right, Mr Jericho. Can't quite put my finger on it, but definitely not right. Still.' He snapped the notebook shut and gave a reassuring smile. "Time to go into all that later, what?' He put his hand on Jericho's knee and pushed himself to his feet. 'First, we must catch our rabbit. You've no idea where she might be, I suppose? No favourite haunts? No little den to run to?' He gazed down at Jericho, who was staring at the floor. 'No? No. Thought not.'

By the time Jericho felt he could trust himself to look up again, Wigram had draped his beautiful overcoat back around his shoulders and was preoccupied picking tiny pieces of lint from its collar.

'It could all be a coincidence,' said Jericho. 'You do realise that? I mean, Donitz always seems to have been suspicious about Enigma. That's why he gave the U-boats Shark in the first place.'

'Oh absolutely,' said Wigram cheerfully. 'But let's look at it another way. Let's imagine the Germans have got a whisper of what we're up to here. What would they do? They couldn't exactly chuck out a hundred thousand Enigma machines overnight, could they? And then what about all those experts of theirs, who've always said Enigma is unbreakable? They're not going to change their minds without a fight. No. They'd do what they look as though they might be doing. They'd start checking every suspicious incident. And in the meantime, they'd try and find hard proof. A person, perhaps. Better still, a person with documentary evidence. God, there are enough of them about. Thousands right here, who either know all the story, or a bit of it, or enough to put two and two together. And what kind of people are they?' He withdrew a sheet of paper from his inside pocket and unfolded it. 'This is the list I asked for yesterday. Eleven people in the Naval Section knew about the importance of the Weather Code Book. Some rum names here, if you stop to think about them. Skynner we can exclude, I suppose. And Logie – he seems sound enough. But Baxter? Now Baxter's a communist, isn't he?'

'I think you'll find that communists don't have much time for Nazis. As a rule.'

'What about Pukowski?'

'Puck lost his father and his brother when Poland was invaded. He loathes the Germans.'

'The American, then. Kramer. Kramer! He's a second-generation German immigrant, did you know that?'

'Kramer also lost a brother to the Germans. Really, Mr Wigram, this is ridiculous

'Atwood. Pinker. Kingcome. Proudfoot. de Brooke. You… Who are you all, exactly?' Wigram looked around the tiny room with distaste: the frayed blackout curtains, the tatty wardrobe, the lumpy bed. For the first time he seemed to notice the print of the chapel above the mantelpiece. 'I mean, just because a bloke's been to King's College, Cambridge

He picked up the picture and held it at an angle under the light. Jericho watched him, transfixed.

'E. M. Forster,' said Wigram thoughtfully. 'Now he's still at King's, isn't he?'

'I believe so.'

'Know him?'

'Only to nod to.'

'What was that essay of his? How did it go? The one about choosing between your friend and your country?'

'"I hate the idea of causes, and if I had to choose between betraying my country and betraying my friend, I hope I should have the guts to betray my country." But he did write that before the war.'

Wigram blew some dust off the frame and set the print carefully back on the top of Jericho's books.

'So I should hope,' he said, standing back to admire it. He turned and smiled at Jericho. 'So I should frigging well hope.'

After Wigram had gone, it was some minutes before Jericho felt able to move.

He lay full length on the bed, still wearing his scarf and overcoat, and listened to the sounds of the house. Some mournful string quartet which the BBC judged suitable entertainment for a Sunday night was scraping away downstairs. There were footsteps on the landing. A whispered conversation ensued which ended with a woman – Miss Jobey, was it? – having a fit of the giggles. A door slammed. The cistern above his head emptied and refilled. Then silence again.

When he did move, after about a quarter of an hour, his actions had a frantic, fumbling haste. He carried the chair over from the bedside to the door and tilted it against the flimsy panelling. He took the print and laid it face down on the threadbare carpet, pulled out the tacks, lifted off the back, rolled the intercepts into a tube, and took them over to the grate. On top of the little bucket of coal beside the hearth was a matchbox containing two matches. The first was damp and wouldn't strike but the second did, just, and Jericho twisted it round to make sure the yellow flame caught and grew, then he applied it to the bottom of the intercepts. He held on to them as they writhed and blackened until the very last moment, until the pain obliged him to drop them in the grate, where they disintegrated into tiny flakes of ash.