Convinced that he is somehow responsible for the death of his sister, Guillaume turns himself in. Initially, Detective Chief Superintendent Gabriel Lacroix doubts that Guillaume is the culprit. But more and more evidence pointing to Guillaume as the killer comes to light. First, there is a scarf covered in Manon's blood that Benoît finds in Guillaume's room. He quickly brings it down to the police station. The zeal with which Benoît presents the police with evidence that incriminates his brother puzzles both Alexandra and Céline, Guillaume's wife. Céline is painfully aware that, for some time, her husband has been telling her lots of lies.