Mortelle randonnée (1983)

The agency where the middle-aged private detective Beauvoir "The Eye" (Michel Serrault) works is hired by a couple to follow their son that is meeting a woman. Beauvoir is a bitter man that misses his daughter Marie that was taken by her mother years ago, leaving behind only a photo. Soon he finds that the youngster is having an affair with the gorgeous Catherine Leiris (Isabelle Adjani) and Beauvoir imagines that she might be Marie. Out of the blue, Beauvoir sees Catherine dumping the body of the man in a lake, but he does not report his finding. He follows Catherine who travels to another place and discovers that she is a serial-killer who misses her father and kills her lovers. Beauvoir protects Catherine and falls in love with her. When he finally meets her, he invites Catherine for a drink after hours. What will happen to them?