A boy asks forensic medicine for information on the cause of a friend's death and a few days later he too is found dead. In the den that they believed to be Imardi, our friends find his corpse: someone has walled him up alive. Carlo and his friends start the investigation all over again and arrive at Leonardo Sfera whom Marta, Muzo and Nusco many years earlier arrested for the murder of his girlfriend, Xenia, one of the girls who prostituted herself for Imardi. (thetvdb.com)