Richard Stuart is a very wealthy man, thanks to his methods of 'assisting' certain people to advance in their careers. However, he's blackmailing all of his clients and every now and then he invites them to Las Vegas for a poker game, at which he gets his money from his clients. Thanks to one of Richard's schemes, David Benson's brother committed suicide, and David bursts into one of these 'poker parties' with a gun and attempts to shoot Richard but is overpowered and thrown out. Later that night, Richard is shot with David's gun and David is arrested for the crime. David's young daughter Melanie had followed him to Las Vegas, and when he's arrested she runs to Perry Mason, who is in town with Ken for a boxing match. Perry knows of Richard's methods, and as he wants to know the truth he sets out with Della and Ken to solve the mystery but Melanie wants to help too and gets herself in major trouble with one of the suspects