On October 16, 1984, the body of 4-year-old Grégory Villemin is found in the Vologne river; journalists report the case all across France while officers follow the trail of a mysterious person who had been harassing the victim's family.

New evidence allows judge Lambert to identify a potential suspect in the death of Grégory; the arrest causes trouble within the Villemin family.

While officers believe that the culprit is Bernard Laroche, a witness retracts their confession, bringing the case back to square one.

The investigation is assigned to the regional police of Nancy, lead by commissioner Corazzi who believes that the child's mother is guilty.

Christine Villemin begins a hunger strike to protest her imprisonment; following the advice of her lawyer, she publishes a book to defend herself, but this strategy backfires.