Margaret Lockwood

Frances Gray

Dane Clark

Bill Casey

Marius Goring

Commandant Anton Razinski

Naunton Wayne

Mr. Hedgerley

Wilfrid Hyde-White

Mr. Luke

Eugene Deckers

Alf

Olaf Pooley

Detective-Interrogator

Gladys Henson

Attendant

Paul Hardtmuth

Priest

Michael Hordern

Lab Director Owens

George Benson

Sandwich Stand Customer

Eric Pohlmann

Joe - the bartender

John Horsley

Customs Officer

Patric Doonan

Customs Man

Jill Balcon

Wardress (uncredited)

Ernest Butcher

Tom - Lab Assistant (uncredited)

Anton Diffring

Officer at Station (uncredited)

John G. Heller

Soldier at Station Check Point (uncredited)

Sam Kydd

Customs Man (uncredited)

Richard Marner

Soldier on Train (uncredited)

Anthony Newley

Operator (uncredited)

Dinah Sheridan

Train Passenger at Checkpoint (uncredited)

Ewen Solon

Enemy Scientist (uncredited)

Emile Stemmler

Soldier at Station Checkpoint (uncredited)