Unusual for a British movie of this period, this was filmed in four weeks in Paris.
The J. Arthur Rank Organization planned to dupe the public into thinking that the attractive pairing of Jean Simmons (Victoria Barton) and Dirk Bogarde (George Hathaway) was mirrored in real-life. One of the taglines was "Presenting the stars of Laguna azul (1949) and Londres 999 (1950)." Both Simmons and Bogarde were coming from three film projects that were critically and commercially successful around the world - Simmons coming hot from the one-two punch of Hamlet (1948) and The Blue Lagoon; Bogarde having just finished The Blue Lamp for Ealing Studios, and both were signed to a multi-picture co-starring deal with the Rank Organization. This backfired suddenly, however, after Simmons became involved with Stewart Granger, and Bogarde was afraid of disclosing his own same-sex attraction because of fears of homophobia. The highly touted screen pairing of Simmons and Bogarde lasted only one film.
After watching this film, Howard Hughes became entranced with Jean Simmons and bought her contract from the J. Arthur Rank Organization.
This story mimics Hitchcock's La dama desaparece (1938), which he later filmed for Into Thin Air (1955) in season one of Alfred Hitchcock Presents (1955). The show starred Sir Alfred Hitchcock's daughter, Patricia Hitchcock. The change to the plot being that the girl arrived in Paris with her mother instead of her brother.
The same story had been used as part of the German silent portmanteau horror film Unheimliche Geschichten (1919), directed by Richard Oswald and starring Conrad Veidt.