Passport to Treason is a 1956 British second feature[1] mystery thriller directed by Robert S. Baker and starring Rod Cameron, Lois Maxwell, and Clifford Evans.

Monthly Film Bulletin said "Opening with the private detective wandering through a London fog, this thriller goes on to introduce the corpse (stabbed) clutching the book with a vital clue, the private nursing home equipped with a good stock of "truth drug," the equivocally placed heroine, and the gun battle in a dockside warehouse.

"[6] Picturegoer wrote: "Rod Cameron, fhe Western he-man, made the trip to England to star in this espionage melodrama, set in London.

"[7] Variety wrote: "Passport to Treason is a run-of-the-mill British whodunit with little to recommend it for the American market ... story line is blurry and frequently burdened by incomprehensible English dialog. ...

"[10] The Radio Times Guide to Films gave the film 1/5 stars, writing: "Western star Rod Cameron should never have packed his passport to play the private eye in this dire British B-feature with its sub-Hitchcockian plot about neo-fascists in London concealing their activities within an organisation for world peace.