In 1939 off the New England coast, the submarine USS Squalus is accidentally sunk during a training exercise, killing half her crew.Coming to the rescue is the USS Sculpin, in many ways the Squalus's twin.The remaining crew aboard the Squalus are saved in a lengthy, white-knuckle operation, and 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 aircraft carrier, the greatest of all enemy ships.Never before has an American submarine taken down a carrier.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 the sole survivors of an attack on the USS Sculpin, the very boat that saved the Squalis-turned-Sailfis