The screenplay concerns an American intelligence officer who goes undercover and infiltrates a ring of Nazi spies.

The film opens with war correspondent David Bannister marrying Joan during an air raid in England.

David becomes a radio reporter and does an exposé on the Nazi connections of an American industrialist who is an associate of Alicia Rolf, Joan's close friend.

David's suspicions worsen when he discovers Joan has received a telegram telling her about an espionage bombing on the West Coast.

David and his taxicab driver friend, Mike, trail Joan to a meeting with Carl Gordon, who was also a passenger on the sunk liner.