Inspired by the Dutroux affair, the series begins with the transfer of Guy Béranger, a child killer, to Vielsart Abbey. There he has to serve the rest of his sentence, much to the protest of the inhabitants of the village. The young Brussels agent Chloé Muller is given the task of keeping an eye on the detainee. Barely a month after Béranger's arrival, a girl is found murdered in a local chapel. The murder bears some resemblance to Béranger's actions and appears to be the work of one of his admirers.