Young U.S. Navy Commander Sheffield has his nuclear-armed fast-attack submarine taken over by renegade sailors who are certain there has been a devastating exchange of nuclear bombs while they were without radio contact. It doesn't help that one of them was snubbed for Sheffield's promotion. They have the ship's doctor drug Sheffield to keep him in his quarters, giving them opportunities to load and launch the sub's nuclear warheads at targets in Russia in retaliation for their perceived war. Meanwhile, steely Admiral Justice works topside to have the sub torpedoed before it can start a real nuclear war.