Coliandro believes that Gamberini has relapsed into the old habit of gambling and, trying to help his friend, infiltrates a clandestine gambling ring. In doing so, however, he blows up an investigation already underway promoted by Longhi and puts Giacomino, who he has hired as a consultant, Gamberini and himself in grave danger. Thanks to the help of Ambra, the girlfriend of one of the criminals, the inspector still manages to get away.