Jack nodded. “He’s right. Sorry Valery, I need you to sit tight for the time being. We can all get out to stretch our legs once Greg and Cate have done a quick reconnoiter.”

Mironov’s face remained devoid of expression as he retook his seat, and the huge Yegor turned to look briefly at him, his shelf-like brows folded down over dark eyes. A look passed between them.

Cate turned and shrugged to the Russian billionaire then got to her feet. She saw something behind his eyes that was unreadable, and after a moment he gave her a small phlegmatic smile, and went back to his bank of tiny screens

She leant on the back of Jack’s chair, staring out at the glistening rocks. She knew there’d be a cliff wall back in the darkness, somewhere, but Prusalka’s lights barely illuminated anything beyond the first fifty feet.

Jack looked up at her. “Be careful out there, okay?”

“‘I’ll be fine,” Cate said too quickly. She looked down and saw the genuine concern on his face, and felt like a heel. She put a hand on his shoulder. “Don’t worry.”

“Wait.” Dmitry held up a finger. He went to a storage cabinet built beneath one of the metal desks and returned with two flashlights. They were the type where the handle could be split into a circle that could be worn on the forehead like a caver’s light. He quickly tested both, and then held them out. “Very good luck.” He grinned and bobbed his head.

Jack half turned. “Dmitry, you follow them up and keep watch.”

Dmitry nodded, and then paused. “And what do I do if I see something?”

Greg paused. “See something?”

“What do you do?” Jack asked. “Well, one, you tell them to get back to the Prusalka; and two, throw a wrench.” Jack grinned.

The submersible gently eased in beside the rock platform.

“Plenty of water – still fifteen feet beneath us.” Yegor cut the engines. He sat back, and folded his arms. “Okay.”

“You’re good to go, people.” Jack got to his feet, catching Cate’s eye. “Find out what the hell happened up there.”

Cate waited as Dmitry raced up the ladder to push open the heavy steel hatch, and then jumped back down, his boots clanging on the steel deck. Warm, peaty-smelling air swirled into the vessel, and Cate raised her chin and inhaled – foreboding and inviting. She placed one hand on the ladder, hesitated for only another second, and then was first up the steel rungs.