Lorenzo, director of a drug rehabilitation center, asks for the help of Agent Valli to discreetly solve a crime that took place in the center: a former heroin addict now a night watchman was found dead in the warehouse. Irene is worried because her sister Valeria, Stefano's mother who has not yet managed to detox, also lives in the farmhouse and she fears that she may be implicated in the affair. A criminal gunsmith is found brutally murdered in the back room of his front shop. The agents of the 10th Tuscolano investigate and a neighbor recognizes Petrocchi from the signs, an elderly thief expert in safes, now on semi-liberty. The man denies being in the business but a nasty surprise awaits him.