Tokorev was one of the Russian navy’s longest-serving and most decorated submarine captains, which was why he’d been given command of the Soviet Union’s latest nuclear-powered submarine on its very first shakedown cruise. The sub was so new it hadn’t even been named. Yorsh was the unofficial moniker for its new class—the official one was Project 671. Launching a boat without a name was the worst bad luck if you were a superstitious sailor. Tokorev was not, and anyone on his skeleton crew of thirty who was could comfort themselves that Project 671 hadn’t technically launched yet because it didn’t technically exist.

If the Yorsh passed its sea trials it would be the first of a new fleet of nuclear-powered attack subs. At ninety metres long, with four decks and a pair of VM-4P pressurised water nuclear reactors that could push it to a cruising speed of thirty-two knots, it was larger and faster than the US Permit-class nuclear submarines that had been in service since 1961. And, equipped with both Type-53 torpedoes and cruise missiles, it was better armed than the next generation of Sturgeon-class boats the Russians knew were currently being built in shipyards on both American coasts. It could also stay underwater for eighty days without resurfacing, and was sheathed in a new generation of anechoic anti-sonar tiles that rendered it practically invisible at depth.

The Yorsh also had another trick up its sleeve: an experimental extremely-low-frequency communications system that was designed to let it stay in contact with its home base in Murmansk without needing to surface. The system, codenamed ZEVS, used two long ground dipoles buried in the Arctic tundra outside Murmansk to transmit ELF waves that could be received by submarines in deep water. Because ZEVS worked at just 82Hz it could only send rudimentary signals, and the submarines it talked to still had to use traditional surface communications to confirm or query the orders they received. But if the system’s initial tests with the Yorsh proved effective, it could provide a huge advantage for the Russian navy in its endless game of underwater cat and mouse with the Americans.

Tokorev had been told by a member of the Party a good twenty years his junior before the Yorsh had left its wet dock that it was imperative that everything went right on its maiden cruise. Tokorev had bluntly told the man that every captain of every boat on the planet knew full well that they were responsible for making sure their mission was a success and their crew came home safe and alive.