Etienne Ronsard, a humanitarian surgeon, arrives in Colmar to understand the circumstances of the death of his son Gilles, head of the city's Crime Brigade. As soon as he arrives, he finds the corpse of a man, decked out in a strange medieval-inspired costume. Anaïs Lacombe, the new head of the brigade, questions Etienne as a witness. When she discovers her identity, she becomes confused. Indeed, she thinks that Etienne's son, Gilles Ronsard, is responsible for the death of her fiancé, also a member of the Brigade. He was driving under the influence of narcotics during the accident that cost them their lives. Etienne Ronsard, although cold with his son for several years, strongly doubts the conclusions of the investigation. Gilles was not a drug addict. Etienne will get nothing, neither from the Lieutenant nor from the Prosecutor: the case is closed. Etienne knows that it is never too late, he hopes to convince Anaïs to open the file of this tragic accident again, and to prove, with her, that the two beings they loved did not die for nothing.