Natural Enemy.

Set in Brittany, a detective called Nicolas Luhel is asked to unravel the circumstances of a teenage boy's death. The main suspect is the boy's father. Shattered by the suicide of the main witness, Nicolas lets himself get snared by the strange and fascinating influence that the father exerts on everyone around him. Eventually, Luhel discovers the truth about the murder and feels that the law is inadequate to deal with it. As a consequence, he decides to destroy the evidence and keep it a secret.