The screenplay is written by Jacques Deray, Alain Delon and Christopher Frank based on the novel Le Petit Bleu de la côte ouest by Jean-Patrick Manchette.

The story is about Michel Gerfaut (Delon), charming professional card player who out of nowhere becomes involved in some retribution between weapon traders of high level.

Gerfaut is followed by two hitmen who saw him at the crash site and mistakenly assumed that he is a mercenary hired by competing armament manufacturers to sabotage the deal.

After several attempts on the lives of him and his girlfriend are made, Gerfaut flees and follows a series of clues that eventually lead him to the head of the conspiracy, an arms dealer named Emmerich.

[3] The Japanese distributors reportedly cut the finale where Delon is assassinated and thus gave the film a happy ending.