October 16, 1984. The body of Grégory Villemin, 4 years old, was found drowned in Vologne. While journalists flock from all over France, the gendarmes, led by Captain Sesmat, follow the trail of a mysterious crow who has been harassing the child's family for years...

While the gendarmes believe they have the culprit for Grégory's death in the person of Bernard Laroche, their witness reconsiders his confession, which seems to bring the investigation to a standstill. But new unexpected witnesses quickly bring to light a new theory...