A neutral merchant ship is torpedoed by a German U-boat and the six passengers escape in a life raft and rescue the captain of the U-Boat. They land at a light house and the German radio's for help, but there is a German spy and British spy amongst the passengers, but who is who and are they male or female? This is less of a war film and more a closed house mystery as it plays out in the confines of a light house.