Commissioner Diamant investigates the murder of two black girls. They were sacrificed, hanged, their faces covered with a Malian ceremony mask.

Commissioner Diamant investigates the murder of two black girls. They were sacrificed, hanged, their faces covered with a Malian ceremony mask. Daniel Cisse and his father, who came from Mali twenty years ago, are among the first suspects. Diamant asks for help from Professor Nessim Taiev, an ethno-psychiatrist, specialist in psychic disorders among migrants.