“Acknowledged. We’ll use the time to collect a water sample.”

“Overshot our targeted submergence point? What the hell does that mean?” Ben ranted as he reactivated the Valkyries, the sub’s exterior lights guiding us to the surface. “If you ask me, it sounds like somebody topside screwed the pooch. My money’s on the dumb Viking.”

“Shut up, Ben.” I watched our bow lights’ beacon cut a path through the clear, dark waters until our nose popped free of the surface.

We were surrounded by a dense fog. I aimed our starboard light overhead, but the beam failed to reach the bottom of the ice sheet. “It’s gotta be up there somewhere.”

“Zach, use the sonar to ping the ceiling.”

“That won’t work.”

“Yes it will. The computer can calculate the distance between the air and the ice by the time it takes the sound waves to hit the ice sheet.”

“Do it, Zach,” Ming chimed in.

I positioned my headphones over my ears, activated the sonar station and pushed the red ACTIVE button, sending a loud ping echoing across the surface in all directions.

The acoustic reflection bounced off the ceiling, and the computer pinpointed the bottom of the ice sheet—112 feet above our heads.

Ben swore from his perch behind me. “A hundred and twelve feet. Houston, we have a major problem.”

“Captain, please calm down. Whatever the problem is, we’ll resolve it.”

“Ming, in order to return to the surface we were simply supposed to activate the lasers and launch bow-up out of the water. As the hole opened Vostok’s water pressure would drive us straight up like a geyser. That entire premise was based on the ice sheet being accessible. A 112-foot ceiling isn’t accessible. Are we supposed to grow wings and fly up to it?”

“Stay calm,” I said, my pulse pounding. “We know the first Valkyrie went down and came right back up. That means the bottom of the ice sheet isn’t uniform.”

“Zachary’s right,” added Ming. “We simply need to locate the first drone’s exit point.”

“All right, Doc, I’m buying what you’re peddling, but riddle me this: if the Barracuda launched from the same starting point as the Valkyrie, then how did we end up here, wherever here is? Something must have altered our trajectory.”

“Agreed, but remember the Valkyrie drone is basically a tethered laser with no variables to account for. The Barracuda’s trajectory is subject to a thousand possible weight displacements during the descent. Even the three of us leaning to one side could have caused us to deviate miles off course. In a worst-case scenario we can always have Vostok Command send down a second unit so we can track its splashdown. We’ll be fine.”

Ben exhaled a sigh of relief. “I knew there was a reason I brought you along.”