American naval forces are using a port in Iceland as a base for anti-submarine patrols to protect North Atlantic convoys from Nazi subs. The Nazis send undercover agents into the port in a scheme to blow up the entrance to the harbor and keep the patrols blocked in. The officers in charge of the patrols have to find the spies and stop them before they achieve their objective.
Bruce Bennett
as Capt. Morgan
Virginia Field
as Lida Adams
John Beal
as Carl Hansen
Clifford Severn
as Sandy Brown
Larry Parks
as Gregory
Lloyd Bridges
as Bert
Victor Kilian
as Otto
Hans Schumm
as Cmdr. von Smith
Erik Rolf
as Gunther
Eddie Laughton
as Radio Operator
Wilhelm von Brincken
as U-Boat Officer
