“Is this really the best plan?” Silas asked. For the first time, his arrogance was overridden by fear. “Cave diving requires special certification. Perhaps—”

“I teach that certification,” Gabriel cut him off. “I know what I’m doing. We wouldn’t be doing this if there was any other option.”

He shook his head. My heart had begun to pound as I wondered about the degree of danger we were on the verge of confronting.

“It’s the only way.” Gabriel turned on the light at his wrist. “And we’re wasting time discussing it.”

Silas had begun to tremble, and I didn’t think it was from anger at Gabriel. I felt a little sorry for the Scribe.

He might be an ass, but he doesn’t have to be here. He only came because he believes in what he’s doing.

I swam over to him, keeping my voice low. “I’ll watch out for you.”

His eyes widened, but he managed a nod. I gestured for him to swim in our single-file line just behind Shay and before me. If he needed help, it was my guess that other than Gabriel, Shay and I would be his best shot. Shay seemed to take to any new hobby that caught his fancy—and I was just too stubborn to suck at anything I considered a challenge.

Gabriel led us forward at a slow and steady swim. The farther we moved into the cavern, the narrower the passage became. I tried to keep my breaths slow, but I couldn’t do anything about my amped-up pulse. The tunnel was closing around us, becoming ever tighter. The sunlight, which had pierced the cave’s mouth, now faded, leaving us only with the lights strapped to our wrists to guide us.

Gabriel stopped. He didn’t turn around, but his voice bounced over the surface of the water and the tunnel walls.

“We’re going under now,” he said. “Follow the diver in front of you and the guideline. It will take about five minutes before we hit the gap where you’ll have to take off your vest and tank. I’ll be on the other side; you’ll push them through the opening and I’ll light the way with my flashlight.”

One by one we submerged. Unlike the glittering vastness of the open ocean, diving in the tunnel plunged us into a choking darkness. As we swam forward, the passage became less of a channel and more of a craggy, cave-like enclosure with sharp ridges in its walls and stalactites through which we had to weave our way.

Five minutes. Five minutes. Five minutes.

So little time. But the swim seemed to be taking so much longer. We passed other tunnels, offshoots of the path we followed. The current kept shifting around me, pushing and pulling me away from the line of divers. Blood thrummed in my head. I was starting to feel dizzy. Words floated through my mind, a mesmerizing but deadly chant.

Drown. Crush. Lost.

Silas stopped moving forward and the voices in my head began to shriek.

Lost! Lost! Lost!

Why weren’t we moving? What was wrong?

Blood screamed through my veins. I started to turn around. If I could just swim back—get out of this cave. Find my way out, out, out. It was too tight. Too dark.

Silas began to move again. His slow, easy kicks broke through my panic. After a few feet, he paused again. I remained still, watching him, trying to remember what I should be doing.

Behind me, Ren gently tugged the tip of one of my fins. I craned my neck to stare at him. He tilted his head, giving me a puzzled look, motioning for me to go forward, and I understood.

The gap. We’d reached the gap. Of course we’d stop while waiting for each diver to pass through.

My heart was still slamming inside my chest, but my head had cleared enough to stop me short of a full-on freak-out.

But it didn’t do anything to make the wait less agonizing. As our group moved forward, one by one, I couldn’t stop the fearful images that played in my mind’s eye. Getting stuck. Being crushed. Drowning in this darkness.

I gripped the regulator hose with one hand. Right now, it felt like the only connection I had to the outside world—to the light, and earth, and air where I belonged.

Silas was unbuckling his buoyancy vest, wriggling out of it one arm at a time and pushing it and the tank through an opening that I could barely make out. A gap that looked impossibly narrow. Next, the Scribe kicked his fins and slid into the dark hole, his body blocking the flashlight’s beam as it disappeared in the tunnel’s walls. When the tips of his fins were no longer visible, I thought my heart would stop.

A hand reached through the hole and Gabriel’s face appeared. He was waiting, beckoning to me. My mind screamed at me as I separated myself from my vest and tank and guided them into Gabriel’s hands. He’d been right—any type of thinking would work against me, fueling the fear that could kill me.

I forced my mind to go blank, willing my legs to kick slowly, mechanically. Stretching my body, I propelled myself through the narrow gap like a torpedo shot out of its tube.

I didn’t know that I’d made it to the other side until Gabriel gripped my arm tight, helping me through.

He was shaking his head, forcing me to slow to a stop. He held up my vest as I slipped it on. The crinkling around his eyes told me he was smiling. Shay was beside him, waiting for me and smiling as well.

When my vest and tank were in place and the buckles secured, Shay took my hand and we swam to the surface. I ripped off my mask, gulping air and shuddering. Shay pulled off his mask and spit out his mouthpiece, grinning at me.

“What?” I asked.

“You were supposed to go through the gap slowly, Calla,” he said. “You caught Gabriel so off guard you almost knocked the regulator out of his mouth.”

“I just wanted to get it over with,” I said, feeling defensive. That swim ranked high on my list of things I never wanted to do again. When Adne surfaced, I wanted to kiss her. Thank God it’s a one-way trip.

Shay splashed me, still laughing.

Ren surfaced beside us. “Man, it’s good to be able to see again.”

With drowning no longer a threat, I gazed around the cavern. Ren was right. The light was dim, but we didn’t need our flashlights.

“That must be the opening of the cenoté,” Shay said, pointing at the ceiling.

Far, far above us—at least a hundred feet up—was an opening in the cave through which jungle-filtered sunlight spilled into the darkness, flickering only with occasional movement near the opening, a fluttering of birds that nested inside the cavern.

“You guys like swimming that much?” Mason called. He and Nev were sitting a few feet away with Ethan and Sabine. “Dry—okay, not dry, but damp, solid land right here.”