The sub surfaced. To my horror, I found myself staring between swells at the female Purussaurus. The fifty-foot crocodilian was upstream, scrambling onto its belly, its attention focused somewhere overhead. Jaws fixed open, the giant caiman hissed as it reared back on its hind legs, balancing on its thick tail.

For a brief moment I thought the croc would leap. Instead it remained coiled and disappeared from view as the river’s current swept us around a bend.

“This is Vostok Command. Dr. Liao, Dr. Wallace—”

“This is Wallace, stand by.” I leaned over my seat to check on Ben. He was lying on the floor, unconscious.

Reaching to his command chair, I flipped the toggle switch on his joystick, relegating control of the submersible to my cockpit. Strapping myself in, I started the Barracuda’s engine and resurfaced the vessel, keeping our nose pointed downstream.

“Vostok Command, this is Dr. Wallace. What the hell happened?”

“Wallace, this is Colonel Stephen Vacendak at Vostok Mobile Command Post One. Your vessel ran out of air. We were able to resupply you with five fresh tanks and reconnect your umbilical cord. For the duration of the mission you’ll be communicating directly with me.”

“Understood.”

I heard a moan as Ben awoke. “Ugh. My head feels like it was used as a bowling ball. Ming, you okay? Get dressed.”

The privacy curtain to Ming’s cockpit was pulled open. Ben climbed over the back of his seat into his cockpit. “Zach, why are we alive?”

“Ask Colonel Vacendak.”

“Where’s that damn urine bottle? And who the hell is Colonel Vacendak?” Ben put his headphones on. “Hello?”

“Captain Hintzmann, this is Colonel Vacendak in Mobile Command Post One. Are you inebriated?”

“Inebriated? Hell no, I’m shitfaced drunk. Now who the hell are you and how is it that we have a Mobile Command Post that I never knew about?”

“You’ll be briefed at the appropriate time. Is Dr. Liao all right?”

“Yes. What happened, Colonel?”

“We sent Dr. Wallace’s friend on a rescue mission.”

“True was down here?” I glanced back at Ben. “Where is he now?”

“Mr. MacDonald is en route back to the surface in a Valkyrie tow pod. For now, we want you to relinquish command of the Barracuda to us. We’re going to remotely guide you across the plateau through a maze of waterways, then into the northern basin to your extraction point. You have just over nineteen hours of air in your tanks, but we anticipate having you topside in twelve. Any questions?”

“It’s Dr. Wallace. How do we relinquish command?”

“First, you’ll need to give control of the vessel over to Captain Hintzmann. Hintzmann, there’s a red button under a plastic cap beneath your console. Pop open the lid and press the button to activate the remote. Once we take control, your computer screen should change to a GPS map of your surroundings.”