In a silver mine in Ludivika, three girls are found dead. Everything seems to point to a collective suicide. Once Bergman learns that the investigation has been completed by the police following the advice of psychologist Riddarstolpe, he decides to go to the crime scene himself. There Bergman stumbles upon an important clue that the girls in all likelihood had help ending their lives.

Vanja's father dies, while Sebastian is forced to follow the group to Skåne to solve an old case. Ludvig Mattisson was known for abducting and murdering mentally disabled children. Now Mattisson himself has been found murdered. Not far away, a little girl is found dead. Could Mattisson have killed the girl before he himself was murdered? And who was behind Mattisson's murder?