A US Navy frogman and underwater demolition expert is ordered to steal a vital Japanese code book from a Pacific island. The captain of the submarine charged with taking him into enemy waters disapproves of the plan, causing tensions to rise and threatening to jeopardise the mission's success. Second World War adventure, with James Garner, Edmond O'Brien and Alan Hale Jr.

Lieutenant Braden discovers that Sally, the woman he's been falling in love with, has actually been checking out his qualifications to be a U.S. Navy frogman. He must put his personal life behind him after being assigned to be smuggled into a Japanese-held island via submarine to photograph radio codes.