In 1943, the crew of the U.S.S. Tiger Shark, an American submarine in the Atlantic, rescues three survivors of a British hospital ship that came under German attack. One of the survivors, a nurse, raises tensions among the all-male crew from the moment she steps aboard. Commanding Officer Lieutenant Brice does his best to keep the unruly crew in line, but after suffering damage from a barrage of Nazi depth charges a series of increasingly spooky occurrences begin to rattle everybody aboard.
