“I don’t understand,” Greg crowded in beside Cate. “What the hell happened?”

The mountain of tangled remains of the crane was piled on the bottom. Rock, soil and fallen bodies created small islands everywhere.

“That tremor we felt a while back…” Jack stopped the submersible and it hovered in the dark water. “That must have been an earthquake. Maybe we weakened the cave roof, and it collapsed.”

“Hmm, then why would everything look scorched?” Mironov asked.

“We have topside camera.” Dmitry waved Cate over. “Look, hole is bigger.”

Cate rushed to look over Dmitry’s shoulder at the top camera’s feed. At first, it was hard to make out – the circle of light was still there, but instead of the pinpoint of light she remembered, it now looked ragged, uneven and much bigger.

“We should surface,” Cate said. “Maybe we can still get a signal out. Or at least pick one up, and see what happened.”

“Is that a good idea?” Greg asked. “Some of those boulders on the bottom are the size of trucks. What happens if one more decides to drop down on top of us?”

“We risk it,” Jack said. “Take her up, Yegor.”

The big Russian was frowning so deeply, his brows formed a single massive shelf over his dark eyes. “I don’t think so.” He turned his head slowly to Jack. “You look.” He pointed one of his blunt fingers at the radiation counter on his console. It was registering off the scale for plutonium particle count.

“What…?” Jack sat back, rubbing both hands up through his sweat soaked hair. He turned as Mironov cleared his throat.

“Now I think it becomes clear,” the Russian billionaire said evenly. “Why the bodies were burned up, why all the destruction, and why the localized tremor we felt. I suggest, there has been a detonation of some sort of tactical nuclear weapon on the surface – small, compact, undoubtedly low yield, of maybe even less than a single kiloton. But enough to totally obliterate the surface crew.”

Mironov looked at his own monitors, which were duplicates of many of Yegor’s and Dmitrys. “And by the look of that heavy particle count, I‘d say it was an enhanced radiation weapon – a dirty bomb – designed to maximize the ionizing particles. Poison the area.”

Cate sat down before her legs gave way. “They didn’t want to just destroy our means of escape, they wanted to salt the earth to ensure we never could.” Cate folded her arm tight cross her chest, feeling chilled even in the humid cabin. “Even if we got scrubbers in, it’d take months or even years to clean it up.” Her eyes welled up. “We’ve got days.”

“Very bad.” Dmitry rubbed a hand up over his shaven head. “Someone wanted to cut us off.”

“Someone did cut us off,” Greg shot back. “But why? Why would they do that?”

“Why and who?” Jack’s lips compressed.