Violette Bushell is a young woman whose father is English, and whose mother is French, living in London early in the Second World War.

Eventually she is reunited with two other women agents she had befriended during their initial training, Lilian Rolfe and Denise Bloch, in a Nazi prison.

When the train is bombed by Allied aircraft, the women have a chance to attempt to escape, but Szabo instead fetches water for male prisoners.

[6] With her blonde hair and handsome angular features, Virginia McKenna bears no resemblance to the real Violette Szabo, a brunette with dark eyes standing at less than 5 ft. 5 in.

[7] McKenna gives Szabo a marked south London accent brushed with received pronunciation, her performance being in the tradition of the "stiff upper lipped" strictly class-structured heroine that would be anticipated by audiences in the atmosphere of a pre-Bond 1950s Britain.

[8] The film itself, released in 1958, does not show the full horror of Szabo's treatment in captivity, especially in Ravensbrück concentration camp, or the true manner of her execution, but it gives a broad impression of her bravery and fortitude.

[9] Szabo was described in the citation to her posthumous George Cross as having shown a "magnificent example of courage and steadfastness", by her daughter, Tania, in the title of her 2007 book about her mother's missions, as "young, brave, and beautiful", and by fellow SOE agent, Odette Sansom, GC, who survived Ravensbrück, as "the bravest of us all".

Denise Bloch and Lilian Rolfe were fellow SOE agents, and were executed with Violette Szabo on 5 February 1945 in Ravensbrück.

Vera Atkins, Odette Sansom, and Leslie Fernandez, one of Szabo's SOE instructors and a field agent himself, were advisors on the film.

The role played by Paul Scofield, Tony Fraser, was created for dramatic purposes, but is based upon Szabo's actual male colleague on her missions to France, and organiser of the Salesman circuit, Philippe Liewer ('Major Charles Staunton').