Diana, played by Béatrice Altariba, is a minion of the maniacal assassin Diabolicus in the 1962 Italian comedy film "Totò Diabolicus".
At the beginning of the film, Diana is working on getting married to the old Marquis Galeazzo di Torrealta. One morning, she discovers what she believes to be Galeazzo's body (killed with a knife, and with a note that reads "Diabolicus") and screams. During the police interrogation, she argues that she wouldn't have murdered Galeazzo since he was about to change his will in her favour, thereby clearly showing her gold-digging intentions.
Later in the film, Galeazzo reappears and explains to Diana that it was in fact the body of one of his brothers, a member of the clergy: Monsignore Antonino di Torrealta, who looks like his brother except for his white hair, which Galeazzo had tinted dark before killing, thus making everybody believe the body was his own. Galeazzo turns out to be Diabolicus, who has already killed a number of Galeazzo's lookalike brothers. His plan is to continue to kill his last remaining brother, to then take on his identity and thereby ensure that he himself is the only surviving brother. Diana decides to stick with him, feeling she is in for the money again.
Galeazzo then lures another of his look-alike brothers into a trap, planning to kill him and dress him up as the Monsignore while at the same time taking his place, Diana watches Galeazzo kill his brother and then helps him by tinting the body's hair white. As it turns out, however, the body does not belong to Galeazzo's brother, but to a private detective sent by the brother to take his place, wearing a mask.
While tinting the hair white, Diana had overlooked that the hair was not real but belonged to a mask covering the detective's hair and face. Both Galeazzo and Diana are discovered red-handed by the police and presumably arrested.