The film was based on a novel by Robert Gaillard about the real life Jacques Dyel du Parquet which sold over 150,000 copies in France. The novel was published in the US, the first of Gaillard's novels to be so.[3]
Belinda Lee's casting was announced in March 1959.[4] It was one of a series of biographical roles she played in Europe.[5]
Magali Noel fractured her ankle during filming in August.[6]