The film stars Jeanne Moreau and Maurice Ronet as illicit lovers whose murder plot starts to unravel after one of them becomes trapped in an elevator.

[2] The improvised soundtrack by Miles Davis and the relationship the film establishes among music, image, and emotion were considered groundbreaking.

Shortly afterwards, Julien's car is stolen by Louis, a young small-time crook, and his girlfriend Véronique, a flower shop assistant.

Assuming Julien could not go through with their plan and has picked up Véronique, Florence wanders the Paris streets despondently all night, searching for him in local bars and clubs.

He follows them to a motel just off the highway, and the German driver, the jovial Horst Bencker, invites Louis and Véronique to have a drink with him and his wife Frieda.

She finds Véronique and Louis drowsy, but alive, and accuses the young couple of murdering the Benckers, before calling the police with an anonymous tip.

Florence enters the lab, and Commissaire Cherrier shows her the photos of her and Julien that were on the roll as evidence of the lovers' crime.

Malle cast Jeanne Moreau after seeing her in the Paris stage production of Tennessee Williams' Cat on a Hot Tin Roof.

Scenes of Moreau wandering down the Champs Elysees at night were shot on fast film from a baby carriage using only available light from the street and shop windows.

Miles Davis's score for the film is considered by many to be groundbreaking,[2] with jazz critic Phil Johnson describing it as "the loneliest trumpet sound you will ever hear, and the model for sad-core music ever since.

Davis had just abandoned his first great quintet of 1955–56, including saxophone player John Coltrane, due to their addiction to heroin.

[5] Additionally, Davis, during his time performing, had been experiencing an immense amount of racism and enjoyed the chance to leave the United States for a while.

[4] Davis chose to use musicians he had been performing with on his European tour: saxophonist Barney Wilen, pianist René Urtreger, bassist Pierre Michelot and drummer Kenny Clarke.

"[4] The mood of the soundtrack is described as generally "dour and somber",[9] but the pace is picked up on tracks such as "Dîner au Motel".

The songs "Générique" and "L'Assassinat de Carala" feature Davis's distinctive trumpet style that is echoed through dire straits or death wish motifs.

Davis opened up a new gateway between composition and improvisation in this soundtrack, a pathway which he would explore in the 1959 modal jazz album Kind of Blue.

The website's critics consensus reads, "Louis Malle's hypnotic debut is a noir with genuine soul, infusing its tale of best laid plans gone awry with wistful performances, swooning cinematography, and a sultry soundtrack.