Unusually, the overall ambience of the film is one of sympathy towards the killer, seeing him as a basically good person, and victim of circumstance.

As such, the film marks a vital transitional moment in the move towards the British New Wave cinema exemplified a few years later by A Taste of Honey.

It received widely positive reviews from critics, and was a commercial success, helping to launch a then-11-year-old Hayley Mills acting career.

The landlord reveals that Anya left several weeks ago and owes back rent, even though Bronek was sending monthly payments to her.

Frustrated by Bronek's long trips at sea, Anya has been seeing a married older man, a sportscaster named Barclay.

Gillie who had been playing in the staircase with a banger, hears the shouting and witnesses the murder as she peeks through the apartment door's letter box.

Bronek plans to depart the next day on a Venezuelan merchant ship, the Poloma; for the night, Gillie leads him to a hiding place in the countryside, where he entertains her by re-enacting his overseas adventures.

Under police questioning Barclay admits to having visited Anya's apartment the day she was shot, making him a prime suspect.

Some picnickers find Gillie at the country hideout and take her to the police, where she continues to lie, identifying Barclay as the murderer.

With Barclay as the suspect, she admits that she saw the crime and re-enacts it for Graham at the apartment, but accidentally reveals that she knows the killer is Polish.

Nevertheless, Graham attempts to arrest Bronek, but the ship's captain prevents him, saying that his navigation officer has plotted Poloma's position as just outside the three-mile limit, and therefore beyond the jurisdiction of the British police.

The film was based on a short story Rodolphe et le Revolver by French writer Noël Calef.

Director J. Lee Thompson originally intended to film it that way and in August 1958 sent a copy of the script to John Mills, with whom he had worked on Ice Cold in Alex and wanted to play the part of the detective.

After lunch he told Mills that he wanted to change the role of the boy to a girl and cast Hayley in the part as "the whole story will be much more moving and touching in every way.

Regarding daughter Hayley's acting abilities, John Mills said when they started filming "I simply couldn't believe what was happening.

"[7] Filmink called it "a terrific thriller-drama from Thompson’s peak period, which benefits from location shooting, confident handling, and, most of all the performance of Hayley Mills.