Curiously enough, the central plot of this one is quite similar to that of ONCE A THIEF (1965; also starring Alain Delon and which I watched on the very same day) though here it's even gloomier (ultimately taking the form of a plea against capital punishment)! Incidentally, co-writer/director Giovanni had been a convict in real-life, and even wrote the novel which inspired Jacques Becker's marvelous prison-escape drama LE TROU (1960).
Anyway, Delon and Jean Gabin are well-teamed here (this was the last of three films in which they appeared together, following ANY NUMBER CAN WIN [1963] and THE SICILIAN CLAN [1969]): the latter isn't particularly exerted by his role being, after all, among his last but the former is unusually committed and, in fact, he also served as the film's producer! Mimsy Farmer appears as Delon's new lover following the tragic death of his wife in a road accident; Michel Bouquet is memorable as the Javert-like police inspector who won't let Delon go (a slinky but nastier version of the Van Heflin part in ONCE A THIEF); Gerard Depardieu has a brief role at the beginning as a wannabe criminal associate of Delon's.