Remus Lupin (Moony): Also a friend and schoolmate of the Potters, Lupin is a full-fledged werewolf not an Animagus and professor of Defense Against the Dark Arts. For 12 years, he resided as the Weasley's family pet Peter Pettigrew (Wormtail): Studied at Hogwarts with Black and the Potters. Sirius Black (Padfoot): A dog Animagus, an old friend of Harry's parents and Harry's legal guardian Still a wanted wizard, Sirius goes into hiding, and Harry sadly returns to the Dursleys. Harry then conjures a powerful Patronus charm to save Sirius. The Dementors find Sirius and are about to suck his soul when Hermione magically turns back time.

Sirius, it turns out, is actually Harry's godfather. But Harry soon discovers that Peter Pettigrew once a good friend to Harry's parents and Sirius was in fact responsible for betraying the Potters' whereabouts to Voldemort. When he learns that Sirius betrayed his parents and are to blame for their death, Harry vows to kill him. Harry loses the first Quidditch match of the season when Dementors storm the field in search of Sirius. Harry, Hermione and Ron enroll in Professor Trelawny's Divination class and Hagrid's Care of Magical Creatures class. Hermione exhibits strange behavior and seems to be enrolled in every single class, even those with conflicting times.

At Hogwarts, Dumbledore informs students that the school will be guarded by the dreaded Dementors, Azkaban guards who can suck the souls out of wizards. Weasley warns Harry that Sirius is after him. The wizarding world is also buzzing about the infamous Sirius, who had been held at Azkaban, a maximum-security prison for those who have committed severe crimes. What happens in the book: Harry ends another insufferable summer at the Dursleys and hears about an escaped murderer, Sirius Black, in the Muggle news.

Third harry potter book