The False Step (1965)

Original title: Le faux pas

During a walk along the cliffs not far from Marseille, Elisa Langerot sees her husband slip and fall to his death. Inexplicably, Elisa flees the scene of the accident, stops a passing driver and tells him a made-up story about a stolen car, concealing her husband's death. Feeling sorry for the girl, the driver, Philippe Morçot, gives her a lift and later lets her stay at his house. The good deed, however, doesn't go unpunished, and soon Philippe is drawn into Elisa's twilight world of fantasies, lies and paranoia.