Twelve-year-old Mathieu is haunted by the death of his father, who died accidentally when he was two. On each anniversary of his death, the young boy becomes withdrawn and unusually taciturn. This attitude worries his grandmother, but not his mother, Agathe, a general practitioner, who prefers not to overreact. Things get complicated when Mathieu, fascinated by his history teacher's tales of cursed kings, decides to create his own family tree and convinces himself he is the descendant of a family of men who die young.

When struggling filmmaker inadvertently records a notorious serial killer in the middle of a murderous act, he decides to use the footage to blackmail the madman into being the subject of a disturbing new documentary.