Set in the 1960's when the Cold War had the potential to become very hot, the British Admiralty decides to send one of its Polaris submarines into the Black Sea, which while international waters, the Soviet Union considers its private sea. The purpose of the voyage is to study Soviet defense preparations in the Black Sea.

Almost as soon as Temeraire entered the Sea, it was challenged by a Soviet destroyer and had a torpedo fired at it by a Soviet submarine. During the ensuing battle, the soviets lose two vessels and a damaged Termeraire ends up helpless on the bottom of the Black Sea. The remainder of the novel covers how a Polaris sub survives helpless on the bottom of a sea and the consequences of her voyage to diplomatic relations. The author also works in the domestic problems of the crew and the consequences it has on their work aboard ship.

One learns a great deal about serving on a submarine that is loaded with missiles. ( )