A professor of criminology murders one of her students. She expects to get away with it because for 20 years she's been best friends with the lead detective. The detective wants to uncover the truth, even if it means arresting her best friend.
Detective Louise Bonne and her assistant Fatou investigate a murder at a restaurant. In her personal life, Louise considers reconciliation with her ex husband.
A woman is in a psychiatric facility and an award winning mathematician visits her, saying he will help her escape. When one of them winds up dead, detectives Roche and Majeski expose lies and uncover the truth.