While a burglary takes place in the garage of an old lady, the investigators discover that it is the mother of a serial killer. Soler and Marchal also learn that the burglar has 50% DNA in common with Lieutenant Erwan Lebellec. Faced with this discovery, Erwan is forced to reveal part of his past when ten years ago, his best friend, Johanna Dupieux disappeared. The young woman was allegedly killed by a serial killer but her body was never found...
