Harry Potter and the Prisoner of Azkaban attacked by a big black dog, which Harry has seen several times before. The dog drags Ron through a tunnel under the Whomping Willow into the Shrieking Shack. Harry and Hermione follow, and there is a brief standoff when they find Ron with Sirius Black, who has transformed from the dog. Lupin enters, and they explain the situation to Harry and his friends: Lupin is a werewolf, which led to his friends James Potter, Sirius Black, and Peter Pettigrew becoming animagi. Lupin explains that Scabbers is Pettigrew in his animal form; he has been hiding from Black, whom he had
Harry Potter (film series) for the third film, "Harry Potter and the Prisoner of Azkaban", claiming he was "burned out". He moved to the position of producer, while Alfonso Cuarón was approached for the role of director. He was initially nervous about directing the instalment since he had not read any of the books or seen the films. After reading the series, he changed his mind and signed on to direct since he had immediately connected to the story. Because Cuarón decided not to direct the fourth instalment, "Harry Potter and the Goblet of Fire", a new director had to be selected. Mike Newell