The examining magistrate from Saint-Clement-Sur-Cher relocates to Paris and is assigned to the Vampire case and the Moréno affair. After being summoned to the magistrate, Moréno commits suicide using a concealed cyanide capsule. His body is left in his cell, but during the night he wakes up, very much alive. He kills the night-watchman and takes his clothes, escaping from the prison. He is noticed by Mazamette, who is suffering from insomnia. The following morning, Moréno is found to have escaped. While writing an account of the events, Philippe is pulled out of his window by the Vampires and whisked into a large costume box. He is driven away and the box is unloaded, but incompetently, and it slides down a large flight of stairs. The Vampires retreat and Philippe is let out by two bystanders. He visits the costume designer Pugenc whose name and box number (13) are on the costume box, just missing Moréno and his gang who have bought police uniforms for a scheme of their own. Philippe learns from Pugenc that the costume box was to go to Baron de Mortesalgues on Maillot Avenue, and realizes that “Mortesalgues” must be another alias of the Grand Vampire. Later, Moréno confronts Philippe in a café, but when Philippe calls for the nearby policemen, they turn out to be part of Moréno’s gang and he is again captured. Meanwhile, Mazamette breaks into Moréno’s hideout. Philippe is taken there to be hanged by the gang, unless he can give them means to revenge themselves against the Vampires. He tells them that Baron de Mortesalgues is the Grand Vampire, and they spare him, tying him up. Mazamette appears and frees him. That evening, the Grand Vampire, in disguise as Baron de Mortesalgues, holds a party for his “niece”, who is Irma Vep in disguise. The party attracts many members of the Parisian aristocracy. “Mortesalgues” reveals that at midnight there will be a surprise; but the “surprise” is a sleeping-gas attack on the guests. The Vampires steal all of the guests’ valuables while they are unconscious. The Vampires flee with the stolen items on the top of their car, but Moréno, forewarned by Philippe, robs the Vampires and sends Philippe a letter telling him that, for the moment, they are even. Mazamette visits Philippe; he is angry with their lack of progress and wants to quit. Philippe opens a book of La Fontaine’s Fables and points to the line, “in all things, one must take the end into account”, and Mazamette’s resolve is renewed.