Dirk looked up and saw a faint ripple of silver far above their heads. They were now close enough to reach the surface if Summer’s air failed. But now they had another problem.

Exposure to the pressurized depths allows tiny nitrogen bubbles to form in the body’s tissue. If not allowed to dissipate via a gentle reduction in pressure, the gas bubbles can lodge in the body, creating the agonizing and sometimes fatal malady of the bends.

Dirk estimated they had spent close to fifteen minutes on the seafloor. The Navy Dive Tables called for multiple decompression stops, but they had no such luxury. They ascended to what Dirk guessed was about twenty feet and then held their position. Their natural buoyancy and the swift current made it a challenge, but he kept his eye on the surface and fought to keep them in place.

They milked the tank for another ten minutes before Summer spat the regulator out of her mouth and pointed up. They both shot to the surface, exhaling as they swam.

Their heads broke the surface amid a choppy sea dotted with whitecaps. The sun had already vanished, leaving the sky a darkening shade of pewter. The combined effects would render them almost invisible to a passing ship, even one that was searching for them. Yet that wasn’t first on Summer’s mind.

Sucking in a deep breath, Summer turned to her brother. “A flagpole?”

“Best I could do, under the circumstances. How’s the foot?”

“The foot’s okay, but I have a painful cramp in my ankle.” She shot him a concerned gaze. “I don’t think we came anywhere close to covering our deco time.”

Dirk shook his head. “No, we were well short. Do you feel any tingling anywhere?”

“I’m too numb to feel much of anything.”

“We might be sleeping in the Alexandria’s decompression chamber tonight.” He scanned the horizon. “Our next problem.”

They finally spotted the NUMA vessel far to the west. The dark band of the Madagascar shoreline was visible a bit closer, to the north.

“The Alexandria is up current,” Dirk said. “No way we can swim to her.”

“They’ve probably swept by already and are backtracking with a sonar survey to locate the submersible. We’ll have drifted to Australia by the time they get back this way.”

“Then to shore it is,” Dirk said. “Are you up for the swim?”

“Do I have a choice?”

She eyed the coastline, put her face in the water, and started swimming. They were both excellent swimmers in fit shape. Under normal circumstances, the open-water swim to shore would have been little more than a tiring challenge. But the mental strain of their escape from the submersible, combined with their cold-water exposure, turned it into a life-or-death task. Fatigue struck both swimmers almost immediately. Summer couldn’t believe how quickly her arms and legs felt like they had turned to lead.