Time Out says
Belmondo, owner of a cigarette factory on the African island of Réunion, advertises for a wife, gets Deneuve (who isn't what she seems), falls in love, and finds himself embroiled in a succession of crises and suspicions. Derived from Cornell Woolrich's novel Waltz into Darkness (a title that effectively matches at least one aspect of the film), this belongs to the group of Truffaut films that includes The Bride Wore Black and A Gorgeous Bird Like Me; it's an elaborate, low-key thriller-fantasy that strains and modifies, comments on and fondly sends up pulp fiction, while taking pulp fiction's more mythic elements as its base. Gags multiply. And at the film's centre, remaining firmly in the mind, is Belmondo's Louis, ensnared, almost ensnaring himself and loving it, the victim of recurring nightmares in the Clinique Heurtebise.