In Roubaix the severed hand of an unknown boy is found. Niemans and Camille are scheduled for the case. Locally, Niemans learns that three women were cruelly murdered in the village. Although local police authorities don’t want any interference in the investigation, Niemans makes additional inquiries on its own initiative.
The trail leads them to the Home of St. Vincent, a facility for children from problem families. It has a bad reputation, not least because there were a number of child abuse cases in the 1990s. When Niemans and Camille spend the night there to get a closer look, on a nocturnal tour, Niemans was almost knocked off from the roof of the building by an unknown person, but thanks to Camille can save himself at the last second.
In the investigation of a series of burglary, which was apparently committed by a gang from the asylum, they locate the owner of a rifle, which was probably used in the serial murders. Since the gun was stolen from him and the fingerprints found in the burglaries coincide with those of the severed hand, Nieman's suspicions that both cases are related are compounded.
