In the middle of the gallery was a green EXIT sign and a pair of fire doors.
Ben ran for them. He snatched the doors open and started to run down the white marble-tiled stairwell. Somewhere below him, he heard running footsteps — so many that it was like distant machine-gun fire. And shouting and screaming, louder now. He went down past one door, then another, then another. Floor after floor went by. The sounds grew louder. Ben kept his hand on the black handrail, counting down the floors, swinging round and round as he went. Floor five … four … three.
He caught up with a small group of people, who barely looked at him, all intent on getting out. They were half jogging down the stairs, not daring to run fast but too frightened to walk.
When they reached the second floor, they saw a man wearing a red armband printed with the words FIRE MARSHAL. He was waving people in through the open fire door, like a policeman directing traffic.
Ben caught a glimpse of something further down the stairwell. Something black, glossy and moving. The building was full of water. He wondered with a sinking feeling in the pit of his stomach whether Cally was still down there.
‘In here, please,’ said the fire marshal, and Ben obeyed.
It was a big, open-plan room, which took up nearly the entire floor of the building. It was full of people sitting in chairs, on desks, leaning against the window ledges. They looked calm and orderly, all waiting patiently. The ones who had just arrived were joining a queue and filing past another fire marshal, who was ticking off names on a list.
Ben joined the queue. He felt better now that he was with people, reassured by the queues. OK, he thought. Maybe we’ll all be all right. But there was a smell in the room: cold sweat and fear.
There was another smell too — something salty, tarry. And a sound, like gentle splashing. The water was lapping just below the windows.
It was Ben’s turn to be checked on the register. Another fire marshal peered at him. ‘Who are you?’ His list of personnel ran to several pages. The building must have thousands of people working in it.
‘I’m a visitor,’ said Ben.
‘Who were you with?’
‘Cally—’ Ben realized he didn’t know her surname. ‘Cally in Clean Fuels Research.’ He looked around the room, hoping to catch sight of her.
The pen scanned up and down the list, over the page, found a name and hovered. ‘Is she with you?’
Ben hesitated. ‘No.’
‘Where is she? She shouldn’t have left you alone. Visitors shouldn’t be unaccompanied. Where is she?’
Ben didn’t want to say. His throat was dry. It took him a few goes to get the words out. ‘She went to a meeting in the basement.’
The fire marshal didn’t look up. He kept his pen over Cally’s name for a moment, then put a dot in the margin next to it. Ben stared at it.
Then the man waved him on.
A woman sitting at a desk beckoned Ben over. Beside her was a big green first aid kit; a man in glasses was dabbing antiseptic on a gash in his arm. ‘Have you got any injuries?’ she asked Ben.
He shook his head. ‘No. I’m fine.’
‘OK. Find a seat and wait for instructions.’
Ben did as he was told. He approached a group of people who were sitting chatting. They looked almost unconcerned, though he noticed that one had a bruise over one eye. Most of them had rucksacks or bags with them, and coats. He passed some people who must have escaped from the flood water outside too — a woman was rubbing her legs with a towel; her companions’ jeans were wet up to the knees; high-heeled boots lay discarded on the floor, the leather soaked through. It grew darker as Ben made his way towards the middle of the floor, away from the windows. He could see tiny patches of light as people used their mobiles as torches to read, or listened to music or played games.
A slim woman with her hair covered in a headscarf spotted Ben. ‘What’s happening?’ she asked.
‘I don’t know,’ said Ben.
A plump woman in a long skirt, wet up to the knees, answered her. ‘The police said to stay here and we’d be evacuated.’
Ben leaned on the window ledge and looked across to the Houses of Parliament. Now that he wasn’t so high up, the river looked even more vast. A plume of sparks rose into the sky like fireworks. What was it — an electricity substation shorting out? He got out his phone again. The display said there was no signal.
‘You won’t get anything on that,’ said a voice.
A balding man in a light grey suit was watching Ben morosely. There was something smug about the way he said it, as if he was enjoying Ben’s disappointment.
‘No harm in trying,’ said Ben cheerily.
The balding man looked taken aback and moved on. Ben was suddenly reminded of the louts he’d met on the train, seeing what they could do to upset the other passengers. Perhaps one day the pierced bullies might be wearing suits and going bald. That made him smile.
He looked out of the window again. Big Ben said ten to two; his watch said two fifteen. Then he knew the world really had gone wrong: Big Ben had stopped.
A loud bang and a flash shattered the hushed conversations. Ben, along with all the people at that end of the floor, found himself instinctively pushing away from the explosion. All around him he heard screams.
After a few moments everyone stopped and looked back, like wild animals that had been spooked. A cupboard was belching thick smoke into the room. Sparks of orange-yellow and blue light showed behind the door.
Then the chaos started. Everyone began to talk at once. ‘The sprinklers will come on in a minute.’
‘They won’t. They’ll have shorted too.’
The light show continued behind the cupboard door. ‘All the electrics are on fire in there.’
Then Ben noticed that one of the windows was open; a thin man in a dark, sweat-stained shirt was sitting on the window ledge, looking down at the water lapping at the white marble building just a couple of metres below.
Ben remembered the helpless figures hurled by the tide against the concrete walls outside. He pushed through the group of people and seized the man’s arm.
‘Don’t,’ he said.
The man looked at him angrily. ‘I’m a strong swimmer — I can get to that rail bridge over there.’
Ben kept his voice calm and looked into the man’s eyes. ‘I just saw someone die doing that. They must have thought they could make it too. The current is too strong.’
The man’s colleagues were obviously also having doubts. ‘Don’t, Richard,’ said the woman with the wet gypsy skirt. ‘There must be another way.’
Richard sighed, then got to his feet, turned and carefully lowered himself back into the room.
Suddenly the door of the burning cupboard burst open and smacked against the wall. Smoke billowed out, along with a smell of burning cable. From the floor above there was another bang.
As the crowd surged away from the fire, Ben gradually found himself swept to one side. His elbow caught a door handle and he stumbled backwards into an adjoining room — a small meeting room.
The stinking cloud of smoke followed him in …