A civilian film crew goes along on a routine sea patrol of the United States nuclear-powered attack submarine USS Hyman G. Rickover (SSN 709). Also, retired submarine commanders and military experts discuss the tactics and strategy of undersea warfare, from the early days of World War I to the revolutionary changes brought on by atomic power. Interviews with the crew of the Rickover help us understand why they endure the danger, loneliness and confinement of submarine service.