Hellhole: An Anthology of Subterranean Terror

THE DEVIL’S THROAT Rena Mason

Dr. John Blake’s gloved hands floated between striated rock walls as he swam through the ancient lava tube toward Shelf 5. The color footage went gray before white horizontal bands rolled down the video screen.

Cyan leaned toward the glass and tapped the monitor. “What the—”

Static blasted from the speakers. “Bloody hell!” she said, jumping back.

“Dr. Blake?” Kau said, his timid voice unexpected from his broad, Māori physique.

Cyan slid the microphone from Kau’s hold. “John, what’s happening?”

“Wellington, we have a problem.” Fear skirted John’s voice.

She hated his Kiwi versions of Yankee phrases. They’d met in Corpus Christi, Texas during a Fossil Fuels Drilling and the Environment Conference, and bonded through marine biology, genetics, and ocean science. A perfect match since research consumed ninety-five percent of their lives.

A hazy image froze on every screen in the control room, and then all systems went down.

“Kau, get him back online!” Cyan rushed to the power box and flicked switches.

Kauri Tāmihana, the communications specialist, pounded the dash with his massive fist. Tribal tattoos rippled up his arm as a metallic clang resounded off the aluminum walls. Cyan glared at him from the other side of the room.

“Oops. Sorry.”

As it quieted, they tuned their ears into the silence. Panel lights flickered then steadied. Some blinked red.

Mackenzie Brown’s voice came over the loud speakers. “Sorry ‘bout that, Cy. Generator’s fucked.”

“Mack, get your ass to comms.” Cyan hunched over Kau’s shoulder and watched him reboot. “Can you pull up—”

The last bit of feed from John’s camera blinked onto his computer, cloudy and fixed.

“Thanks,” she said. “But can you clear it up and get it in color?”

“That is color.”

Cyan scrutinized the picture. “Are those knots?”

“Black ones?”

“Video cables?” she said. “Did he get tied up in old equipment?”

“What’s going on?” Kauri’s wife Maia, the station’s cook, stood in the doorway.

“Dr. Blake’s A/V stopped working,” Kau said.

“I’m sure it’s something you did.” Maia dried her hands with her apron. “Can I help?”

A towering shadow shifted behind her. Mack moved Maia aside and walked in.

“You can go,” Kau said to his wife.

“What’s wrong with the generator?” Cyan looked up at Mack.

“Couldn’t find anything specific,” Mack said. “Seems to be happening more. I’ll check the cooling systems. Might have to call mainland engineering in to have a look.”

“Anything yet?” Cyan rested her hand on Kau’s shoulder.

Kau shook his head.

“Dammit. I’m suiting up.” She headed out.

CYAN SHADED HER eyes as she stood on the curved dive entry deck of the partially submerged Rori Underwater Research Facility, built for the scientific study and genetic manipulation of rori — Māori for sea cucumber — for their water filtering abilities. From the air, RURF had the shape of a puzzle piece: two circular areas at bow and stern and the entire deck constructed of long teak planks. The center housed solar panels arranged like flower petals above the generator, pumps, cooling systems, and everything mechanical to do with running RURF. Comms, the lab, kitchen, and their quarters, edged the perimeter. Ballast tanks lined the underside, ocean water pumped in and out to stabilize the platform on the sandy bottom, cooling the equipment and providing air conditioning. Every year scientists and engineers from all over the world visited RURF, a foolproof engineering marvel until now.

Twenty-two meters out, a dark blue circle of calm water separated Cyan from her husband, Dr. John Blake.

Whooping helicopter blades blew golden strands of blonde into her face. “This can’t be good.” She pulled her hair into a ponytail and hurried to get her gear on.

The chopper landed on the pad, deposited four men in uniform, then took off again. Cyan hadn’t even zipped her wetsuit when one of them approached.

“Dr. Blake!” he said.

She ignored him and tugged on the cord behind her, using the helicopter noise as a good excuse to pretend she didn’t hear him.

His footsteps rattled the boards under her bare soles. “Dr. Blake. I’m Captain Richards.”

Cyan huffed and turned around. “Captain, I don’t have time… What are you doing here? Never mind. Talk to Mack, he’s in charge of whatever’s going on with the generator. I’m going in.”

“No, you’re not. Ensign Smith is. I have orders to—”

Kau’s curly black hair came up the stairwell, followed by the rest of him. “What’s going on?”

Cyan checked her tank, put her vest over the top of it, then latched it into place. “Kau did you call these guys? Maybe Mack did?”

“He’s still working on the generator.”

Richards stepped in front of her. “Dr. Blake, at zero, eight, thirty-seven hundred hours your husband set off a sensor at Shelf 9. We were deployed immediately as that’s a violation of—”

She stopped fidgeting with the regulator and gauge hoses. “What are you talking about? Besides being physically impossible, we never go past the third shelf,” she lied.

Within the last few weeks, they’d noticed more productive filtration coming from the sea cucumbers the deeper they went. They’d needed more specimens to study the anomaly. That’s why John had gone down to Shelf 5, a restricted area only because of its sixty-meter depth.

Underwater caves and lava tubes branched off the main vent of a dead volcano and then ascended onto dry land shelves further inside. The shelves contained breathable air, making it optimal for human exploration.

Richards’ team carried and rolled big black cases and trunks to the dive entry deck. They set them down near her gear and prepped equipment onto a frame she’d always wondered the purpose of. It appeared these men had more familiarity with RURF than she did.

One of them, Ensign Smith she presumed, already had on an NZDF issue black wetsuit. “Oy, why’s your gear strapped to nitrox if you ain’t going past thirty meters?” he said.

Cyan pointed at Kau and lied some more. “He brought me the wrong tank. See, we’re all in a bit of a rush to get to John.”

The other two Defence Force members pulled a large helmet from a box and attached it to Smith’s odd, hybrid atmospheric suit. It sealed with a click and a hiss. Before she could ask, Ensign Smith stepped into the water carrying a large pack, blasting up plumes of creamy sand and silt.

Asshole.

“Where’s your operations room?” Richards said. “My men need to link the A/V.”

“Captain, I don’t care who you are, we’re not switching John’s feed to yours.”

Richards reached for his sidearm. “I have orders to—”

“John’s is still down,” Kau said. “I think it’ll be okay if they use it.”

“Thanks a lot, Kau.” She’d said it sarcastically, but he likely just saved her ass.

“Sorry.” Kau shrugged and lowered his head.

“Show these men to comms. I’ll be there soon.” Cyan glanced at the sword and writing on their uniform patches.

The men followed Kau below. She peered over the deck and watched Ensign Smith approach the blue hole, leaving a milky ocean behind him.

“Come back, John,” she said. His diving skills ranked in the pro level, and they’d stored plenty of nitrox tanks on the shelves for deeper dives, but she worried anyway. Cyan stepped away when dark water caught her eye. The sunlight and waves distorted everything under the surface, so she squinted and lay prone with her head over the deck.

Ensign Smith’s landing had shifted the cover of hundreds, maybe thousands of black sea cucumbers, Holothuria leucospilota. Cyan had never seen such a dense population before and wondered how far they spread around RURF’s platform. Long white strands, their innards, or Cuvierian tubules, undulated below. Like her, they saw Smith as a threat and went guts out, a self-defense mechanism. She’d see the ensign eviscerated before doing that to herself. Dozens stuck to his boots and legs. No wonder he made such massive silt clouds. Cyan headed for the engineering room. She needed to calm and think straight, not that she’d get that from Mack.

The Aussie was up to his neck in a panel box when she arrived.

“Is that a good idea?” she said.

His head banged gray aluminum as he backed out. “Ouch.” He rubbed his skull in quick circles. “You told me to look into it, and that’s what I’m doin’.”

“So, what’s the story with the pumps?” Cyan leaned against a post.

“I can’t figure. Says they’re functional. Pressure’s right. We’re still running on stored battery power though, and the cells won’t last more than a day or two. We’ll have to shut down energy suckers like the lab. And pray clouds don’t roll in.”

“You call someone out?”

“Thought I heard a choppy topside. No way it’s those engineering dills. So, who’s here?”

“Military. But not like I’ve seen before. There’s a long sword on their insignia. Innovative and Agile or something it reads at the bottom. You were Anzac. Know it?”

Mack scratched the stubble on his chin with the wrench in his hand. “Hmm… Special Ops Forces. What those diggers want with RURF?”

“It’s something in the blue hole they’re after. They’ve already sent a man down.”

“I’m sure they’re just here to rescue John.”

“Captain Richards said they came because John triggered an alarm on Shelf 9. Why would they have alarms down there?”

“They’ve had control since its discovery. RURF’s crew’s the first non-military they let go near it,” Mack said. “How far down you think their secret project goes?”

“I don’t know. Deeper than we can venture with our gear.” Cyan took in a breath then exhaled. “Honest, I don’t give two fucks what’s down there, Mack. I just want John back.”

“And you trust these diggers’r gonna do that?”

“Come up with me. There’s something I need to show you. I have a bad feeling about John, and we can’t leave Kau alone with those soldiers for too long or he’ll give away all my lies.”

“Bloody natives.” Mack smiled but kept the wrench in his hand as they headed out.

Cyan didn’t question his weapon of choice. Topside, she showed him the dark water, now spread beneath RURF. Off the bow, exposed rori cut a black road to the blue hole.

“Fuck all. What’re they doin’?” Mack stared down. “Looks like they’re headin’ out on holiday to feed the rēwera o korokoro.”

“Don’t call it that! John’s down there.” Cyan lowered her eyes and waited for them to focus. “Dear god. Their motility—”

“So much for inching along the bottom with their little feet.”

“They can’t be advancing that fast!”

Fixated, Cyan and Mack followed the movements of the rori horde, raising their heads to the blue hole, or as the Māori call it, the devil’s throat.

IN COMMS, RICHARDS gave orders to his men, as well as Kau.

“What’s all this?” Mack said.

Laptops from more of their black cases sat atop of the control dashboards, linked by wires and cables.

“Oh, hey,” Kau said. “These guys have some cool equipment, you should see—”

“That’s classified,” Richards said. “A need-to-know only basis, and they don’t need to know. We’re square on that, right Tāmihana?”

“Okay. Yeah. Sorry.” Kau went back to typing on one of the military keyboards.

All the screens blinked on with rock wall shaded in blue hues. Cyan walked over to a laptop monitor that displayed Smith’s vital signs. “I see what you mean by cool, Kau.”

“I’m coming up on Shelf 3, sir.” Ensign Smith’s voice came through cleaner than she’d ever heard. “Permission to head in?”

“Wait,” Cyan said.

“Is there something you want to tell me Dr. Blake?” Richards smirked.

“John was going to Shelf 5. We needed specimens from that depth to—”

“Negative, Ensign. Head to Shelf 5.” The captain turned back to the screen.

Smug bastard.

The live feed had unbelievable clarity. As he descended, floating white streamers ruffled all around him.

“His suit is impenetrable, right?” she said. “Their excretions can be harmful.”

“Yes, ma’am,” one of the soldiers said.

“Thank you, Simms,” Richards said.

“I’ve reached Shelf 5, Captain. Permission to enter.”

“Go ahead, Ensign.”

Cyan sat down in front of a monitor. Mack stood behind her. Ensign Smith hovered in front of the opening.

“Thrusters on,” the other soldier said.

“Affirmative.” Richards watched Smith propel into the cave.

Lights came on, illuminating dark rocky walls.

“Simms?” Richards said.

“All systems functional, Captain.”

Lighter bits of marine life, their excrement or what remained of them, floated in the water like dust motes drifting in air. Cyan synced her breathing to Smith’s.

“Do you see any sign of John?” Cyan knew it was a reach, but maybe he’d dragged the cords from the last image his camera froze on with him.

Smith lowered his head, giving them better visuals of the cave bottom.

“Thank you,” she said.

Sand and silt covered most of the floor. Occasional dark rocks jutted, but no cables, wires, not even a single fish came into view.

“Have you seen anything swimming around down there?” she said.

“Just me,” Smith said. “And this white shite.”

“That’s unusual. Can he? Can you, get a closer look at those rocks?” Cyan hoped they might be rays, skates, or nurse sharks.

Petty Officer Taylor typed on one of the black keyboards. Then Ensign Smith smacked head first against the bottom of the cave. “Dammit, Taylor!” Smith said.

“It’s hard to adjust buoyancy in small spaces. Hang on, or you’ll hit the ceiling.”

Cream swirled past onscreen. White streamers shot up from the sand.

“What the fuck?” Smith said.

“Ensign, report.” Richards leaned toward a monitor.

“Worms. Giant black slugs, crawling on my helmet. Taylor, get me up!” Smith’s heartbeat pounded from the laptop, and his breathing became rapid and shallow.

“Calm down,” Cyan said. “They’re harmless.”

The image went out of focus as Smith’s suit lifted off the cave floor.

“We can’t see them,” Taylor said.

“Switch to the suit cam,” Richards said.

“Yes, sir. Interior camera on,” Simms said.

Black tentacles from the sea cucumbers’ open mouths searched the glass for purchase. Their tubule innards stuck to it in a wrestle, like oriental noodles crammed into a package.

“Fuck, that’s gross,” Simms said.

“Can’t you get them off?” Ensign Smith shouted.

“With what?” Taylor said. “The grabbers won’t reach. Find something after you molt. Just keep your eyes closed. We’ll steer the ADS in.”

“That’s one helluva suit. Clever bastards,” Mack said.

“They’re not aggressive.” At least Cyan hadn’t seen them behave that way before today.

“You sure?” Mack put his face next to hers and stared at the screen. “These look like they’d eat his face if they could get in.”

“Something’s not right,” she whispered.

“Switch back to exterior camera,” Richards said.

Overhead lights flickered, the room vibrated then shook. Cyan steadied a laptop as it slid across the dash. Comms panels rattled around her.

“What’s happening?” Richards said.

“Mack?” Cyan said.

“I’m on it.” He headed out with his wrench.

“Captain, Ensign Smith’s reached the surface of Shelf 5,” Taylor said.

“Atmosphere? Systems?” The captain stepped to the laptop displaying the exosuit’s digital readouts.

“Sustainable, sir. All systems functional,” Simms said.

“Proceed with ADS removal.”

“Smith, keep moving your legs. It’ll feel like you’re walking up a ramp.”

“Do the thrusters work when he’s on land?” Kau said.

“No,” Taylor said. “A specialized hydraulics system takes over. That’s Simms’s specialty.”

“That’s enough, Taylor,” Richards said. “Simms, let’s see what you got.”

“Has the ground leveled off, Ensign?” Simms tapped the laptop keys in front of him.

“Yeah,” Smith said.

“Then sit down where you are and follow standard molting procedures. Take it slow.”

“Affirmative.”

“Okay, suit separation in three, two, one,” Simms said.

Popping then wheezing came through the speakers.

“Systems?” Richards said.

“Stable, sir,” Simms said. “Ensign Smith, you can molt now. Don’t forget to connect A/V to your wetsuit and turn the system on after you crawl out of ADS.”

“Affirmative,” Smith said.

“What’s ADS?” Kau said.

Simms turned to him. “It stands for Atmospheric Dive Suit, but we call ours a mix of names because it borrows ideas from most of them like the Newtsuit, Exosuit, and the WASP. Ours is lightweight, maneuverable, and specially designed for ease of—”

“Shut it, Simms,” Richards said.

“Sorry, Captain.” Simms focused on his laptop.

Richards pressed a key and spoke down toward the monitor. “Any sign of Dr. Blake?”

“Negative, sir.”

Cyan stood. “I wonder what’s keeping Mack.”

Mack’s voice came through the intercom. “Cyan, meet me at the quarters hall.”

“What is it?” she said.

“Now.”

Kau faced her with a concerned expression. “Can you check on Maia while you’re there? I haven’t heard from her in a while.”

Cyan walked toward the door then stopped. “Please, let me know if you come across any sign of John.”

“Yes, ma’am,” Simms said.

LIGHTS CAME ON as Cyan walked down the hall to quarters, but an uneasy darkness there remained thick and unmoving. “Mack? Where are you?”

“In your room,” he said.

“What?”

All sleeping quarters had underwater view windows. Mack had his forehead pressed against the glass. But instead of clear, bright blue ocean with fish swimming by, stacked layers of black sea cucumbers blocked all sunlight. Crawling mouth holes puckered and sucked while their tentacles groped for purchase the way they did on Smith’s helmet.

Cyan shivered. “Oh my god.”

“I may just be the guy who fixes things ‘round here, but I think you’re right, and these dogs are up to something.”

“Is it just this window?”

“Nope. Every one of ‘em.”

“How do you know?”

“Checked. Can’t find Maia either,” Mack said.

“Kau asked me to check on her. What am I supposed to tell him?”

Mack pressed his lips to the glass and kissed.

“That’s bloody disgusting. Get your shit together. We need to find Maia.”

“I think she’s out there,” he said.

“What?”

“Thought I saw her speargun just over there, before these fuckers came and covered the window.”

“That’s impossible. They can’t move that fast.”

“Didn’t you say that topside? About their mass exodus down the devil’s throat.”

“Do you think that’s what happened to John?” Cyan said, holding in a sob.

Mack backed away from the glass. “Let’s find Maia. Then we’ll go after John. She’ll be all right. Don’t you worry.” He led her out by the arm.

CYAN AND MACK circled the deck and met at the stern where they found Maia’s shoes.

“Looks like she went in for our din-din,” Mack said.

“Then where is she?” Cyan scanned the water’s surface. “I don’t even see the float she uses to bring up her catch.”

“Possible she were the one caught this time.” He climbed down and stretched his leg out from the last rung of metal stairs that went into the water. After a minute, he pulled in Maia’s yellow mask and snorkel. “She couldn’t have gone far without these.”

“We’ve got to tell Kau.”

When they stepped back into comms, Captain Richards looked up at Mack. “You figure out what all that rattling was? It’s happened again twice now.”

“Didn’t make it to engineering, cap’n sunshine, but I think I know what the problem is.”

Cyan walked over to Kau and whispered in his ear.

“What?” Kau pushed away from the desk and stood.

“Calm down, mate,” Mack said. “She’ll be right.”

Cyan rolled her eyes. She wished he’d stop saying that. Especially since she knew he thought the rori had killed her. Murdered by sea cucumbers? No way.

“Smith find any signs of John?” Cyan said.

“No,” Richards said. “He’s suited up again and is heading to Shelf 9.”

“Other than the ones he ran into on the bottom of Shelf 5, has he come across any more of the black sea slugs?” she said.

“Three hundred meters down any hole, everything’s black. Is there something we should be concerned about?” Captain Richards glared at her.

“I don’t know, exactly,” she said. “What’s on Shelf 9 that’s so damn important?”

“That’s classified.”

“Then anything I’ve got to say about the slugs is likewise.”

“Where’s Maia?” Kau shouted.

He’d never raised his voice before. Mack and Cyan looked at one another with wide eyes.

Smith’s voice came through the comms speakers. “Heading into Shelf 9.”

They all turned to his video feed. Richards hadn’t lied when he said it was black down there. The cave walls absorbed the light beaming from Smith’s ADS.

“Can you get a close-up of the rock on the sides?” Cyan said.

“I’m in charge here, Dr. Blake. In fact, all non-authorized personnel, leave the room.”

“Piss off, Captain,” she said.

Richards reached for his sidearm. “I’m not asking. Taylor?”

Taylor stood up with a pistol aimed at her.

Mack put his hands up. “Oy. Stay calm, mate. We were just leaving.” He backed up and pulled Cyan along with him. “Come on Kau. Let’s get Maia.”

They left comms ass-first and didn’t utter a sound or turn around until they passed the corner. Cyan broke their silence. “What the hell, Mack? I wanted to—”

“Get shot?” he said. “They’re not going to let any of us see what’s down there. It’s classified. Don’t you get it?”

“He’s right,” Kau said. “I listened while I was in there, playing dumb so they spoke over my head. The military hid something back in the caverns of Shelf 9. Something dangerous.”

“Great,” Cyan said.

“Forget about it. Let’s get some gear on and head down. We need to find Maia and John and bring them back. Then we can figure out what to do about the diggers.” Mack headed for the equipment room.

Kau followed. “You know I’m too big to get into any of that. You two go. I’ll get on the lab computers and set up your A/V. You need me here in case the soldiers try something stupid.”

“They’ve already done that, but you’re probably right,” Cyan said.

“Cy, suit up.” Mack had already donned half his gear. “Put the drysuit on. We don’t want the… uh, cold to get in.”

He loaded their vests onto nitrox tanks and checked the regulators and gauges. The air mixture had to be just right for deeper dives. “I’ll carry these up,” Mack said. “Grab knives, spearguns, lights, flares, and whatever else you can carry.”

“You really need all that?” Kau said.

“I don’t want to take any chances.” Mack headed for the diving deck.

“Let me make sure A/V’s working before you jump in.” Kau walked toward the lab.

After putting on his Predator full-face mask, Mack helped Cyan with hers. “Can you hear me?” he said.

Cyan nodded. “Loud and clear.”

“Copy that,” he said. “Kau?”

A high-pitched squeal, static, and then Kau’s voice came through the Predator’s speakers. “Audio’s solid. Turn each other’s cameras on.”

Mack pushed the button on the side of Cyan’s mask.

“Cy’s is working,” Kau said.

Cyan adjusted Mack’s camera then turned it on.

“Cams are up and recording. The pressure in your suits is good, too. Be careful down there.”

They gave each other the thumbs up in front of the cameras for Kau.

“Fill up,” Mack said. “Let’s float to the hole.”

“I’m right behind you.”

Mack stepped off the deck and into the water. He submerged less than three meters then popped to the surface. She followed him in, eyes fixed on the bottom as they moved toward the devil’s throat.

“You seeing this?” Cyan adjusted her mask.

“Yeah,” Mack said.

“Are those all rori?” Kau said. “They look like they’re moving as fast as you.”

“Reckon that’s ‘cause they are, mate.”

“Doc, what did you do to them?” Kau said.

“Since the Cook Islanders let other countries come and harvest them to near extinction, we genetically altered them to increase filtration. That’s it. The breeding rate and motility of these are… It’s unprecedented. Are you recording all this, Kau?”

“Yes, Doc. But I’ve got a bad—”

“Don’t say it,” Mack said. “We’ll go around the platform and look for Maia.”

The piles of sea cucumbers decreased the original depth of the ocean floor around RURF by five meters. Incredible.

Mack moved his fins in long, steady kicks with Cyan gliding in his wake.

“I’m not seeing any signs of her,” Kau said. “Only the rori. So many—”

“I’m sorry,” Cyan said. “We’ll look again on our way back.”

“You’re right. Go. You’ll need all the nitrox in your tanks to find Dr. Blake. I can look for her, too. Maia’s a good swimmer. Maybe she went further away from the deck then she realized.”

“You’re right about that,” Mack said. “I wouldn’t be surprised if she’d swam all the way to the nearest atoll, looking to bring you home a good sup.”

Talking between them ceased as if they knew she’d gone, giving her a moment of silence. Cyan pictured Kau in the lab, crying. Mack neared the blue hole’s opening and waited for her to catch up. Just the two of them took up most of the circle, its size deceptive compared to what waited below.

“Going in,” Mack said. “Lights on, Cy.”

He reorganized his spearguns. They each carried two with four extra shafts. Cyan turned on her torch and secured the cord around her wrist. At the entrance to rēwera o korokoro, they faced each other, floating upright.

“Ready?” Mack said.

“Let’s go.” Behind him, the darkness of the rock wall moved.

“Look at me,” he said. “Keep your eyes on me as we descend, understand?”

She nodded, grabbed her buoyancy control, and released air in quick bursts from her suit and vest. Sunlight coming through the small opening faded as they drifted down into the devil’s throat.

“With what we’ve got on, we’re going to have about ten minutes of nitrox more or less, plus whatever’s stored in the tanks on the shelf. We might have to take turns so one of us can watch the other,” Mack said.

“What if he’s not there, and went down to Shelf 9 like the captain said? If he’s been at that depth—”

“Don’t think it. Smith’s on nine. If John’s there, he’ll bring him back, make sure he stops and decompresses.”

“Oh, yeah,” she said. “They’ll figure out a way to link up and buddy-breathe.”

“That’s it,” Mack said. “Doc Cy’s back in action. Kau, you reading us?”

Nothing but silence came through the speakers. Most dives, no matter how deep, the ocean always made sounds. A cacophony of fish rummaging and nibbling on coral, and popping and crackling came from all around, even movement of the surrounding water created gulping and swooshing noises. In the devil’s throat, though, silence made a deafening background. So, she focused on her breath sounds, slowing her respirations by listening to her breathing pattern. The deeper they went, the harder the pressure made it to inhale. Cyan often had to remind herself to draw in a breath.

She and Mack stared at one another, and she knew John’s chances by the look in his eyes. Not a bit of evidence marked his way. They’d waited too long.

Static blasted through the darkness and into their headset speakers. Kau panted then stopped. “Doc? Mack?”

“Kau!” Cy said.

“They’re not far behind you.”

“Who?” Mack said.

“The soldiers. They locked me in the supply closet, but I busted out. Something happened to Smith on Shelf 9. They lost comms with him, then came and found me. Saw that you’d left.”

“How many of them?” Mack said.

“All three,” Kau said. “And they’ve got guns. RURF’s been overrun by rori. Biting ones. They knocked out the battery and panels. Internet’s down. I’m using my laptop on deck to talk with you.”

“What?” Cyan shouted into her mask.

“They tore Taylor’s leg up pretty bad, but he didn’t want to stay.”

“You need to get in the boat and head to land, Kau. Get help!” Cyan said.

“I can’t leave you though—”

“The hell you can, and will,” Mack said. “Go now! We’ll find John and shelf up for air and decompression.”

“Mack’s right,” Cyan said. “You’re the only who can get away to call for a rescue. What did the captain say they were going to do down here?”

“Protect Shelf 9 at all costs,” Kau said.

The audio went out.

“Can you hear me?” Cyan looked at Mack who shook his head no.

“Dammit,” she said.

They both looked up, and the opening appeared smaller, as if the devil’s mouth might swallow them whole.

MACK GENTLY ROLLED sea cucumbers back into the water with his boots as they walked up onto Shelf 5. They neither went guts out or attacked him. Mack leaned his spearguns against the cave wall next to a row of ten nitrox tanks then helped Cyan take off her mask.

“Do you think they brought another exosuit with them?” she said.

Mack removed his full-face Predator as well. “Don’t think so. One set of huge cases was all I saw. Unless they had one drop-shipped after we went under.”

“Kau said the backup generator… But they probably have military satellite phones. Maybe they got a call out before it shut down. Please, god. I hope Kau made it.”

“Of course he did. She’ll be right yet. You’ll see.”

“Stop. If you tell me now he likely found Maia snorkeling and picked her up on his way, you’ll lose me.”

Mack laughed. “I’m not crazy, Cy. Maia was hiding in the boat this whole time, and Kau found her when he threw the cover off.”

“I really wish that were true. It would give me more hope—” Cyan looked behind him, up the rocky trail into the cave of Shelf 5. “Come on. Let’s find John.”

A single layer of sea cukes covered the trail. They parted as she and Mack headed in. “How are they surviving on dry land?” Cyan crouched and pointed her torch down then up the walls. “Where do you think they’re going?”

“Hell if I know. These ones look confused.”

He was right. Some slithered deeper into the cave, while others wiggled the other way. One plopped onto her shoulder from the ceiling and she screamed. Mack brushed it off and it fell onto another one, then headed up the wall again.

“Maybe being out of the ocean is affecting their behavior,” she said.

Mack stopped and shined his light along the cave floor. “Why would John go deeper if what he came to get was all around him?”

“You’re right.”

They eyed one another, thinking.

“There’s no way we can get to Shelf 9,” he said.

Shouting and screaming echoed from the entrance. Mack raised his spearguns and rushed toward the calamity. Cyan stood and pointed her torch down the long dark path. “John? I know you’re down there.”

She’d never come this far into the cave before. Her instincts told her to go deeper still.

A gunshot boomed then rang out. “Mack!” Cyan readied her spearguns and ran back the way she came.

Three men stood near the water, one lying on the ground in a pool of blood. Her hands shaking, she raised her speargun.

Mack turned around and saw her. “Stop! These dills shot their own man.”

“He was dead anyway,” Richards said. “We should’ve left him at the first shelf. Those things followed his trail. We couldn’t keep them off him.”

“So you killed him?” Cyan said.

“No. We gave him mercy. Your man topside told us you modified these things. They’re what killed Taylor,” Richards said.

“We need this nitrox,” Simms said. He opened up his laptop case and started typing. “Smith’s still not replying, sir.”

“You can’t have it,” Mack said. “We’re using it to find John. Then we’re heading back.”

“There is no back,” Richards said. “Your platform was on fire when we descended.”

Cyan stepped closer. “And you left Kau there? You bastards!”

“Don’t believe him, Cy. He got away. We’ll find John and then head up.” Mack raised one of his spearguns.

“You won’t win this fight, mate.” Richards pointed a handgun at Mack. “You can either help us, and we all get out, or fight us and die here.”

Something bobbed to the surface at the water’s edge. “I got it!” Simms set his laptop down, went over, and pulled floating pieces of exosuit out onto the rocky ground.

“Is that the one Smith had on?” Cyan said.

Richards nodded.

“Then he must’ve made it onto Shelf 9,” she said.

“Maybe,” Richards said. “Not that it matters much now. Lower your weapons.”

“All right, be calm,” Mack said. “You opened it while he was in it, though? You dag.”

“Oh my god.” Cyan gasped and slipped forward, squeezing her trigger.

A shot cracked the air. Wet heat splattered Cyan’s face. She dropped to her knees. “Mack!” His body fell back with a thud. The bullet left a hole between his eyes. Half of Cyan’s spear stuck out of the captain’s shoulder. He grabbed the base of his neck and winced. “Simms, get this out!”

“It’s barbed, Captain.” Simms grabbed a pair of bolt cutters and a small package from his case then placed the blades around the shaft.

“I’d have pulled it myself if it wasn’t.”

“Okay, then. On my count. Three, two—” He snipped, and the captain howled then swore, spewing saliva from the corners of his lips as Simms dropped the cutter and yanked the metal from Richards’s flesh. He tore open the package and injected white into the hole. Richards screamed as the substance foamed. Simms went around and removed the other half of the shaft then filled the exit wound. Then he dropped the syringe, picked up Richards’s gun, and went back to his laptop. “There’s morphine if you want it.”

“Not before I go down,” Richards said. He glanced at his shoulder, no longer bleeding, then eyed Cyan. “Polyurethane. I don’t think it’ll help your friend, though. Sorry. Involuntary finger twitch to being shot with a speargun.” Richards dragged Taylor’s body to the water’s edge and rolled it in with his foot. Hundreds of rori on the cave floor twisted and flopped in after it.

How were these sea cucumbers surviving on land? They also seemed attracted to blood. They’d covered every inch of Mack while Simms worked on Richards. Cukes slithered over one another on top of his corpse, excreting slick, milky froth, a spawning and fertilization practice that occurs underwater. The DNA manipulations she and John had made shouldn’t have caused these runaway evolutionary developments, and so fast. Her mind raced, but she remained kneeling, unable to move.

Richards put on the upper half of the exosuit. Sea cucumbers climbed his leg, sucking at the blood that had run down his wetsuit. With a few keystrokes, Simms sealed the helmet on. Richards shook his foot. All the rori on him went guts out, shooting white strings like fireworks across his lower extremities. “Get them off!”

Simms yanked them free, chucking their carcasses at the water. He brought over the bottom half of the suit and secured Richards into it.

“You ready, Captain?”

Richards nodded.

Simms went back to work on his laptop. The suit arm pushed Taylor’s bobbing remains aside then descended.

She had a mission to complete too. Cyan scoured the cave entrance, stopping at the nitrox. Her Predator mask and vest sat on the ground nearby.

Simms watched her switch tanks and gear up.

“Where are you going?” he said.

Richards’ voice came through the laptop’s speakers. “Better be Shelf 9.”

“I wasn’t talking… never mind,” Simms said. “I see you’ve made it to the opening. What’s your status?”

“I can’t see anything down here but shit. Like swimming through a long drop with the sea slugs everywhere. Tell Dr. Blake I’ll be reporting her for shooting me with a speargun, and for creating these bloody monsters.”

“Um, yes, sir.”

“Lead the way in, Simms. And make sure she’s not watching the footage!”

Cyan stepped over to the rori cocoon that encased Mack and picked up one of his spearguns. “I don’t think John set off an alarm on 9. The cukes probably did. I’m heading further in to find him.” She pointed at the dark end of the cave with the spear tip. “Try not to bleed while I’m gone. Seems they’re drawn to it.”

“Thanks.” Simms eyed her weapon then glanced down at his guns. “You’d get there faster without all that equipment.”

“I’m taking it with, in case you two decide to head out on your own and take everything with you. But, eh, you wouldn’t want to give me one of those now, would ya?”

“Don’t think so. Besides, I’ve seen your handiwork, and you’re better off with that.”

“Can you tell me now, then,” she said, “what’s down there on Shelf 9?”

“It’s classified. But don’t worry. There’s no chance it’s anything to do with your science project run amok, I promise.”

“That’s bloody reassuring.”

Screams blared through Simms’s laptop. Richards came on, yelling blather about the rori cracking his helmet glass.

Cyan clicked the torch around her wrist and headed in, carrying her mask in one hand, speargun in the other. She didn’t want to be around for the captain’s return.

WHO KNEW SHELF 5 went back so far? Fewer sea cucumbers traveled to and fro along the tunnel the further in she went. After about an hour, her body ached, and she sweated buckets in the neoprene, which sloshed in her boots as she hiked deeper still. Something glinted near a rori. A bolt snap from John’s buoyancy compensator with a miniature US flag attached. She knew he’d gone into Shelf 5. Cyan put the clip in her pocket and carried on.

The cave narrowed, and the hefty tanks bore down her shoulders. Their steel scraped against the rock walls, shoving her off balance from one side to the other. Cyan unfastened the vest and let everything slide to the ground. Then she dragged the gear, hoping the nylon BC wouldn’t snag and tear, harming the inner air bladders.

Gunfire, then shrill screams, bounced off the rock surrounding her. Richards and Simms, she thought. They’d have to wait. Cyan trudged on, and hunched then crawled as the cave walls closed in. When she had to lie prone and pull herself forward, rori inching alongside her, she debated leaving the gear. The torch went out, and Cyan whimpered then cursed. Cold stone met her punching fists, but she avoided striking sea cucumbers on the ground, getting her sad out.

A distinctive blue glow rippled several meters ahead — an easy distance. The tunnel ended in a short drop to a brilliant pool at the bottom of a dome covered with bioluminescent algae. It would be the most beautiful thing she’d ever seen under any other circumstance.

John’s glove floated in the water below.

He’d come this far, and she would too. Cyan stretched and wiggled forward with a firm grip on the gear. Her neck strained to keep her chin and the top of her head from hitting solid rock underneath and above. She inhaled, held her breath, and squeezed out as if the stone bore her.

Icy water stung as she plunged in, gasping for air after bobbing to the surface. The speargun slipped away and sank while she geared up with shaking hands. She turned on the visor light and released air from her BC in bursts, descending into the unknown.

Cyan trembled at the abyss beneath her. No light could penetrate that darkness. Its depth, she hoped, would remain a mystery. Her heart clenched and she forced herself to look away. Light beamed up the wall, revealing a lava tube opening. She spun around and lit up what she could, not finding anything else. The entrance appeared to get smaller as she approached.

Damn. The tanks won’t fit.

After securing her mask and hoses, Cyan once more dragged her equipment along as she pulled forward, propelling through the small tube. Much easier floating with almost weightless gear behind her.

The visor light was bright in the smaller space. In the middle of her mask, swirling salt and fresh water made visibility zero. Just above and beneath the halocline, the separate waters were clear. Fresh water, down here? This had to be an ancient tube. It’s no wonder John had gone to such lengths. But what led him to it?

She hadn’t seen a single rori since the dome pool.

The lava tube narrowed, and the tanks clinked against stone. Exertion quickened her breaths as she pulled her body ahead. Neoprene caught at her chest and scuffed along the bottom. If the space got any tighter, she’d get stuck and have to back out.

Another pull moved her forward and then her upper torso floated in a larger area, possibly a dead volcano vent. Across the way, she saw John staring at her with wide eyes through his mask.

“John!”

Cyan twisted and writhed to be free of the lava tube. She put the BC on, then swam to her husband. His arms floated in front of him. A bare white hand with a missing glove glowed underwater. She pulled hers off and fumbled for his carotid, unable to find a pulse.

“No!” Tears came, then crying, followed by sobbing and choking. “Why, John? Why? We should have left them alone.”

She lowered her head then took his hands, pressed her booties against the wall and pulled. His body budged a little. After a few attempts, she stopped. “Damn you, John! I’m not leaving you here. Help me!”

Cyan braced hard, then yanked, freeing John from the lava tube. His mask bumped into hers and his mouth opened. His jaw moved, and she waited for him to speak.

Black rori young crawled out.

Her mask puffed out with a scream, and she pushed him away.

A cloud of black sea cucumbers encroached John. Cyan took off her vest and kicked until she’d re-entered the tube, pulling her gear along as it tugged the seal around her mask. Cold saltwater rushed in just up to her nostrils and sloshed up with her movements. Hustling, she focused, breathing only through her mouth. Searing pain shot through her skull as she snorted seawater through her nose and bumped her head across craggy rocks. Her chin slammed against the bottom, filling her vision with stars, but she kept going and grabbed whatever felt solid, launching forward, using the tips of her toes to propel.

The tube opened up, but it grew difficult to draw in a breath. Tanks and gages behind, as well as a rori horde, she couldn’t stop to check them but knew the supply had dwindled.

Nitrox from the tanks sweetened and grew colder as it thinned. Her next breath stopped short. Cyan reached out, clutched a rock and pulled, shooting ahead and kicking hard. Fog coated the interior mask. The seal squeezed, and her head pounded. Air!

She reached the dome, nothing coming through the regulator as she kicked upward, the tanks a dead weight behind her. Hitting the surface, she took in a deep wheeze of air that burned her throat and lungs. Without looking back, she climbed the rock face up into the cave.

Pain bit her knees, elbows, and hands, crawling then walking crouched in shredded neoprene over sharp rocks and jagged stones. The cavern’s diameter increased, and Cyan stood and ran. Sea cucumbers massaged her calves as they clung and squirmed over the drysuit. She lost her footing on goo and slid out the tunnel entrance into a wall of rori.

Richards and Simms wrestled, rolling and squashing sea cucumbers as they fought. The exosuit pieces lay near the edge of the water. Cukes mashed as she rolled then crept toward Simms’s gun.

A shot fired, and she froze. Richards kicked Simms’s body into a mountain of cukes, then he spun with his gun aimed. Rori enveloped him from head to toe. Half of one wriggled from his neck, streaming trails of blood down his chest.

“You did this!” Crimson gurgled from his mouth and down his chin. “You and your husband deserve—”

Cyan squeezed the trigger. Saving him from misery.

She pulled herself up and trudged on, ignoring the ocean’s salty sting. Its coolness soothed her sore legs. Exosuit parts scraped rock and squished more cukes as she dragged them out. Cyan shed what remained of her dry-suit laden with carcasses. Leaving her diveskin on, she slipped into the torso housing.

The leg component landed on a wrestle of cukes after she’d thrown it, unable to connect the pieces. “Dammit!” She stomped over, then crouched to pick it up. Rori reached out and grabbed her wrist, human flesh visible beneath the slimy black.

Her screams reverberated as Simms pulled closer. Holes and gouges marred his face. Several rori remained latched there, sucking. Cyan gripped and yanked, lugging him from the pile. His other hand held onto the laptop.

“Put it on.” Simms moaned and swiped cukes off the keyboard with raw skeletal fingers.

Cyan ran and grabbed the other parts, then suited up.

He sealed the ADS then waved her off.

“Thank you,” she said.

Simms typed, and the exosuit came to life and squeaked, pumped air bursts, then moved into the water. Sea cucumbers ebbed and flowed as she swam out of the underwater cave.

Ascending the vent, Cyan exhaled, looked up through cracked class and saw no light.

The devil’s mouth had closed.