A Franco-Italian production, it depicts the intersecting paths of a professional hitman (Delon) trying to find out who hired him for a job and then tried to have him killed, and the Parisian commissaire (Périer) trying to catch him.

Impassive hitman Jef Costello lives in a spartan single-room Paris apartment and keeps a small bird in a cage as a pet.

His methodical modus operandi involves creating airtight alibis, including ones provided by his lover, Jane.

After carrying out a contract killing on Martey, a nightclub owner, Jef is very clearly seen leaving the scene by the club's piano player, Valérie, and glimpsed by several other witnesses.

The police bring Jef and other suspects in for a lineup, but the witnesses, including Valerie, fail to positively identify him.

Back at his apartment, Jef notices some loose feathers scattered around his bird's cage and suspects it was agitated by an intrusion.

He visits Jane and assures her everything will work out, then drives to Rey's house, which is the same home Valérie took him to earlier in the film, though she is not there.

He checks his hat, but leaves his hat-check ticket on the counter, and puts on white gloves, which he wears when carrying out his hits, in full view of everyone.

[5] On Rotten Tomatoes, the film has a 100% approval rating based on 38 reviews, and an average score of 8.6/10; the site's "critics consensus" reads: "Le Samouraï makes the most of its spare aesthetic, using stylish – and influential – direction, solid performances, and thick atmosphere to weave an absorbing story.

[13] Vincent Canby of The New York Times called the original film "immaculate", but criticized the dubbing of the 1972 version released in the U.S. as The Godson as "disorienting" and "dreadful".

[16] Writing in Le Figaro of the Delons' performances after Nathalie's death in 2021, Bertrand Guyard noted that the husband and wife are both nearly silent in the film, but "their gazes, fraught with meaning, are enough to make the camera quiver", and the director was able to create from their portrayals "a mythical couple of the seventh art.