Bête noire the collateral effects of an unforgivable act commited by Jérémy, a 16 year-old teenager. With the help of the psychiatrist-coroner in charge of the investigation, his mother tries to understand how her son, a seemingly normal boy, could commit such a heinous act. What caused this nightmare? When did everything change? Together, the two women try to solve the mystery of Jérémy.

A young man goes to his father's home in Maine where, helped by a public registry, he locates and tracks down sex offenders. In parallel, his mother follows his trail in order to try to understand what could have pushed him into this murderous madness.

February 1927: Félix Leclerc's last year with his family before attending a private college in the fall. Accompanied by Fidor, his faithful friend, he will face adversity, love, death, and will embark on the path of adulthood.