A US Navy submarine, the USS Corsair, is operating in the North Atlantic, hunting German merchant raiders that are preying on Allied shipping. Its new executive officer, Lieutenant Ward Stewart (Tyrone Power), has been transferred into submarines after commanding his own PT boat. At the Naval Submarine Base New London in New London, Connecticut, he asks his new captain, Lieutenant commander Dewey Connors (Dana Andrews), for a weekend leave to settle his affairs before taking up his new assignment. On a train bound for Washington D.C., Stewart accidentally encounters New London school teacher Jean Hewlett (Anne Baxter) and her students. Despite her initial resistance to his efforts, he charms her and they fall in love.