Bush thought quickly. The submerged speed of a Kilo Class was 17 knots. The range of her UGST wake-homing torpedoes, with their 200 kilogram explosive charge, was 22 nautical miles. So the Kilo was already in a position to launch a torpedo at Queen Elizabeth. However, if the Russian sub captain was any good, and he would be good, he’d want to get eyes on his target before launching a torpedo; probably within 10,000 yards, or five nautical miles. That meant Queen Elizabeth could expect an attack in about thirty-five minutes, if that was the Russian’s intent.

How the hell did the sub manage to creep up so close without being spotted? The alarm bells might be sounding in Bush’s head, but the answer was blindingly obvious: We’ve handed ourselves to him on a plate by not having enough anti-sub escorts!

He looked at Narborough. In the narrow gap in his white flash mask between nose and forehead, Bush saw a moment of fear in the Captain’s pale blue eyes. And then it was gone.

Grabbing a microphone, the Captain spoke urgently to the bridge. “Officer of the watch, order damage control state One, condition Zulu. Helmsman, commence zigzagging at maximum speed. That’ll make it more difficult for him to stay with us. Then slow down at random—down to five knots, which will make it more difficult for him to hear us. Get a Merlin with sonar buoy airborne between us and the sub. Now . . . Number One, I’m staying here to fight the ship. I want you on the bridge.”

“Aye, aye, Sir.” Bush saluted briefly and left the Ops Room at speed.

0935 hours, Saturday, May 27, 2017

Control Room, Kilo Class submarine Krasnokamensk, Baltic Sea

CAPTAIN OF THE Second Rank, Alexander Ivanovich Chernavin of the Russian Navy stood in the cramped, darkened control room of Kilo Class submarine Krasnokamensk. To his left, in the confined space, faces illuminated by their plasma screens, was the Ship Control Panel manned by the planesmen, who steered, submerged and surfaced the boat under the close supervision of the Diving Officer of the Watch. Behind them stood the Chief of the Watch. On his right were the sonar operators, who were operating both active and passive sonar. They were keeping a close track of the contact they were following from the sound of its propellers and the noise of its hull as it moved through the water. Beside him stood the Executive Officer, his second in command.

It was warm inside the control room and there was an overriding smell of men’s sweat, usual in a submarine that had been at sea for days. In common with all the crew, Chernavin wore blue, flashproof cotton trousers, trainers and a faded, sweat-stained, blue-and-white striped telnyashka, the long-sleeved undershirt, a legacy of the Tsarist navy; beloved by the submariners of the Russian Navy and considered the mark of elite forces.