After the Cold War, a breakaway Russian republic with nuclear warheads becomes a possible worldwide threat. U.S. submarine Capt. Frank Ramsey signs on a relatively green but highly recommended Lt. Cmdr. Ron Hunter to the USS Alabama, which may be the only ship able to stop a possible Armageddon. When Ramsay insists that the Alabama must act aggressively, Hunter, fearing they will start rather than stop a disaster, leads a potential mutiny to stop him.

Shown from the perspective of a young submariner with unusually sensitive hearing and uncannily precise sound recognition. The fate of many often depends on his ability, and one time, whilst highly stressed, he makes a incorrect call which put his entire crew in mortal danger. Trying to regain the confidence of his comrades, he conducts an unauthorised investigation of an apparent plot which, it turns out, risks escalating into a nuclear apocalypse. Suddenly working under pressure with the fleet admiral, they must do whatever is necessary, even the unthinkable, to prevent a nuclear war, since a confirmed nuclear strike order cannot be countermanded.