Adèle has just dropped off her son Ulysse at school when she meets with a gruesome sight: a woman in blood-covered clothes, standing right in front of the school. She disappears before Adèle can help her. Determined to learn the identity of this woman in distress, the criminologist calls on her colleagues at Crime Investigation Headquarters. She soon learns the lady's life was hit by an awful tragedy. Adèle and Rocher set out to do whatever they can to prevent a new incident from happening.