Il Faut Vivre Dangereusement on AllMovie

Diquet (Claude Brasseur) is a private investigator. Usually, he just follows people around and records what he sees them doing. His latest case becomes progressively stranger. After he is hired to follow a man's young mistress, the detective finds that her journeys begin to tie into his own life -- to episodes dating back to World War II, and to certain of his friends who are dead.