Margaret Lockwood as Frances Gray

Dane Clark as Bill Casey

Marius Goring as Commandant Anton Razinski

Naunton Wayne as Mr. Hedgerley

Wilfrid Hyde-White as Mr. Luke

Eugene Deckers as Alf

Olaf Pooley as Detective-Interrogator

Gladys Henson as Attendant

Paul Hardtmuth as Priest

Michael Hordern as Lab Director Owens

George Benson as Sandwich Stand Customer

Eric Pohlmann as Joe - the bartender

John Horsley as Customs Officer

Patric Doonan as Customs Man

Joan Haythorne as Judy

Jill Balcon as Wardress (uncredited)

Hyma Beckley as Café Mimosa Patron (uncredited)

John Boxer as Police Sergeant at Customs Café (uncredited)

Ernest Butcher as Tom - Lab Assistant (uncredited)

Daniel Brown as Train Passenger (uncredited)

Robert Cawdron as Soldier at Station Checkpoint (uncredited)

Anton Diffring as Officer at Station (uncredited)

Toni Frost as Stewardess (uncredited)

John Gabriel as Night Field Telephone Officer (uncredited)

Charles Hammon as Train Passenger in Platform Line-up (uncredited)

Philo Hauser as Waiter (uncredited)

John G. Heller as Soldier at Station Check Point (uncredited)

Noel Johnson as Frank Conway (uncredited)

Sam Kydd as Customs Man (uncredited)

Richard Marner as Soldier on Train (uncredited)

Louis Matto as Café Mimosa Waiter (uncredited)

Anthony Newley as Operator (uncredited)

Michael Ritterman as The ‘Tail’ (uncredited)

Lance Secretan as Alan (uncredited)

Dinah Sheridan as Train Passenger at Checkpoint (uncredited)

Ewen Solon as Enemy Scientist (uncredited)

Emile Stemmler as Soldier at Station Checkpoint (uncredited)

Robert Vossler as Day Sentry at First Checkpoint (uncredited)

John Wilder as Customs Officer (uncredited)

Billy Wilmot as Café Mimosa Customer (uncredited)