“I knew there was a reason I liked you.” Ren laughed as we swam to the spot where slippery stones of the cenoté floor were lapped by salt water.

I hauled myself out of the water. Only a sense of dignity kept me from sprawling on the stone, pressing my cheek lovingly to the earth. The air was still too heavy, thick with brine and decaying fish, but at least it was real air.

“Everyone okay?” Gabriel asked.

“I’m a little dizzy,” Adne said, squeezing water out of her hair.

“That’s normal,” he replied. “But tell me if it gets any worse.”

“Thanks,” she said drily.

“You all did great,” Gabriel said. “Let’s get what we came for.”

“Where are we headed?” Shay asked.

“An alcove.” Gabriel started walking. “You can see it from here.”

“The light,” Shay murmured.

I followed his gaze. One corner of the cenoté gleamed with the marbled sapphire and emerald tones of the sea that contrasted with the sheer sunlight in the rest of the cave.

Our group began to head after Gabriel, except Silas, who was squinting at the ceiling.

Nev glanced at him. “Yeah, I think our arrival made the birdies unhappy.”

Looking up, I saw what he meant. The flutter of wings above had increased; shadows darted back and forth across the cave’s opening. A tittering sound swelled, echoing in the chamber.

“I don’t think those are birds,” Silas said.

“What?” Nev frowned.

The noise grew louder; sunlight from above winked in and out, at times fully blocked off by the movement above us.

“What is that?” I asked.

Silas whispered something, but I couldn’t quite hear him. The cenoté amplified sound, transforming the fluttering of wings into a rush of wind.

It was too late when I understood he’d said, “Get back in the water. Now!”

FOURTEEN

THE CEILING WAS MOVING, every inch of it.

“Cave-in!” Mason shouted, running for cover.

Gabriel had already leapt from shore, donned his gear, and submerged.

How would getting in the water protect us from falling stone?

Mason hesitated, looking up like the rest of us. The movement above wasn’t a deadly shower of rock; it was swooping, swirling mobs of shadow. For a moment I thought it was wraiths, but wraiths didn’t have wings. And they made no sound.

“Move it!” Ethan shoved me as Sabine dove into the pool. I stumbled backward, falling into the water without my mask on or the first stage of my regulator in my mouth. I came up coughing, struggling to see and to breathe.

Connor and Adne were in the water, like me struggling with their gear.

Gabriel surfaced, ripped his regulator out of his mouth, and shouted, “What the hell are you waiting for!”

Mason, Nev, and Silas were still onshore.

“What’s that?” Nev and Mason both stared at the dark, living cloud—moving slowly toward the water.

“Gabriel’s right—get underwater!” Silas waved at them frantically, even as he fumbled to pull on his own vest and tank. “You can’t stay there!”

His furious movements caught the attention of the swarm above. Suddenly, the cloud of beating wings with its shrill, chirping chorus plunged down. Silas cried out, falling to his knees as it surrounded him.

I could no longer see him, only make out the shape of a body beneath the pulsing mob of tiny furred bodies, leathery wings, and enormous ears that dwarfed their heads.

“Oh God.” Mason grabbed Nev’s hand, dragging him toward the water.

“We have to help him.” I started to swim toward shore, but Gabriel, who was much faster in the water, cut me off.

“He’s already dead.”

“No, he’s not.” I fought Gabriel off only to find both Shay and Ren in my way.

I snarled at them. “What are you doing?”

“Look,” Ren said, jerking his head toward shore.

The cloud had lifted from Silas’s body, which wasn’t moving. The skin I could see was ghastly pale, the rest of it covered with tiny red incisions. Even his wet suit had been cut to ribbons.

“There’s nothing we can do,” Ren said.

“I said I’d watch out for him.” My voice shook. “I said . . .”

“There wasn’t any way for you to know.” Shay glanced at the swarm, which now hovered above us.

I was shivering in the water. It felt as though my bones rattled beneath my skin.

“They’ll dive at us, even out here.” Gabriel watched the swooping mass of fur and wings. “We’ll need to submerge and resurface. That will throw them off.”

I didn’t want to go underwater again. Breathing was already hard enough, and what had happened to Silas had been so sudden, and so horrible.

After we dove down, I heard hundreds of pings on the surface like it had begun to rain. Gabriel led us to the far edge of the cavern. He kept us close, huddled together, arms linked as we waited. At his signal we surfaced.

“Keep your voices low,” he whispered. “And don’t make any loud splashes or sudden movements. The water keeps them at bay, but they’ll still hunt us.”

He gestured to the area from which we’d come. Small winged carcasses floated on the surface. Bats that had tried to get to us, become sodden, and, unable to fly again, eventually drowned.

“Bats?” Mason asked. “Bats can do that?”

“Vampire bats,” Gabriel said.

“But vampire bats don’t kill people,” Nev said. “Right? That’s just a myth.”

“Vampire bats don’t hunt in swarms either.” Gabriel gazed up at the ceiling. “These have been changed. They’re like piranhas.”

“More Keeper tricks,” Shay said.

Connor was gazing at the shore where Silas’s body lay. “Damn it. I knew he shouldn’t have come.”

Guilt tightened my chest again. Why hadn’t I helped him? I could have grabbed him and pulled him in the water.

“What now?” Adne asked.

Ethan looked at the shoreline. “We need to buy Shay time.”

Connor laughed. “You mean draw fire?”

“Exactly.” Ethan smiled grimly.

“Buy me time for what?” Shay asked. “I won’t leave you to fight without me.”