He opened a bulkhead locker and pulled out two complete sets of scuba gear that included full face masks with wireless-communications capability. When they were ready, Phelps climbed up a ladder into a cylindrical chamber. Zavala followed him up, moving slowly under the weight of the gear.

The escape chamber was a tight fit for two men in full scuba gear. Phelps hit a switch that closed the floor, and water poured in. Once the chamber was flooded, he opened the hatch over their heads.

Phelps let air into his buoyancy regulator and swam up the escape shaft. Zavala followed close behind. They emerged from the submarine at the base of the lofty conning tower. The two guards were waiting for them. Each guard held a gas-powered speargun with a nasty-looking barb on the business end. Zavala ignored them and slipped his feet into his fins.

The greenish light that filtered through the camouflage net bathed the black hull of the submarine in a spectral glow. Zavala had once seen a Typhoon at dock, when the hull was mostly submerged, and had been impressed by its size, but that was nothing compared with seeing the gigantic sub and its massive conning tower in full.

A ducklike voice quacked in his headset, and Phelps waved to get his attention.

“That’s enough sightseeing for now, Joe. Follow me. This is a technical dive. Three hundred feet plus, but you’ve got Trimix in your tank, so you’ll be okay.”

Phelps switched on a waterproof dive light. With a fluttering kick of his legs, he swam away from the deck, propelling himself through the water using expert form, and then angled downward. Zavala came next, with the two guards following his bubble trail.

They headed toward an amber cluster of sparkling lights. As they descended further, Zavala saw that the lights were on the outside of four large globes attached to each other with tubelike connectors. He immediately recognized the lab from the diagrams he had studied.

“Davy Jones’s Locker!” Zavala said.

“Quite the sight, isn’t it?” Phelps said.

Zavala noticed something else. Ghostly blue forms were moving slowly in the shadows just beyond the reach of the lab’s searchlights.

“Are those blue medusae I see?” he asked.

“Yeah,” Phelps said. “You want to stay away from those puppies. They’re hot-wired. We can do a nature tour later. We’ve only got a few minutes to talk. We’re the only ones wearing communications gear, so don’t worry about those guys on your tail. I was gonna keep you on the sub so we could work out a plan, but Chang said he wanted you in the lab. Didn’t say what he’s got planned, but, one thing’s for sure, he won’t be throwing you a welcome party.”

“I didn’t expect one,” Zavala said. “How about you throwing me a lifeline?”