James Mason as Peter Vadassy

Lucie Mannheim as Mme Suzanne Koch

Raymond Lovell as Robert Duclos

Julien Mitchell as Michel Beghin, intelligence chief

Herbert Lom as Andre Roux

Martin Miller as Walter Vogel

Clare Hamilton as Mary Skelton

Frederick Valk as Emil Schimler, alias Paul Heimberger

Patricia Medina as Odette Roux

Anthony Shaw as Major Anthony Chandon-Hartley

Laurence Hanray as Police Commissioner

David Ward as Henri Asticot

Valentine Dyall as Warren Skelton

Joseph Almas as Albert, the Waiter

Patricia Hayes as Woman

Hella Kürty as Hilda Vogel

Ivor Barnard as P. Molon, chemist

Ernst Ulman as Detective in Black Suit

John Baker as Policeman

Mike Johnson as Old Man

Victor Rietti as Restaurant Owner

Hugo Schuster as Inspector