Un Flic (1972)

Commissaire Edouard Coleman is a Paris police chief whose life investigating violent crimes has left him despondent. After beginning an affair with a beautiful but cold woman named Cathy, he befriends her boyfriend, Simon, a local nightclub owner. Unbeknownst to Edouard, however, Simon is also a ruthless bank robber and drug smuggler who is planning one final heist. Edouard is forced to pursue Simon after learning his true identity.