In 1939 off the New England coast, the submarine USS Squalus accidentally sinks to the bottom of the sea during a training exercise, killing half her crew. Coming to the rescue is the USS Sculpin, in many ways the Squalus's twin. As their oxygen supply dwindles, the remaining crew aboard the Squalus are saved in a time-consuming, white-knuckle operation. Eventually the sunken submarine is raised, repaired, and returned to duty, with a new name: the Sailfish. Four years later, on patrol during the darkest days of the Pacific War, the Sailfish's radarman picks up the tell-tale signs of a Japanese convoy, known by U.S. intelligence to include aircraft carriers, the most formidable of all enemy ships. Never before has an American submarine taken down a carrier--much less in the middle of a typhoon. Immediately, the crewmen swing into action, embarking on a deadly game of cat-and-mouse as this once-dead boat evades enemy cruisers to stalk closer and closer to their prized target. Little do they know that aboard the Japanese carrier are survivors of an attack on the USS Sculpin, the very boat that saved the Squalus-turned-Sailfish back in '39.