| Director | Alfonso Cuarón |
|---|---|
| Budget | $130 million |
| Box office | $810.6 million |
During another unhappy summer with the Dursleys, Harry Potter becomes enraged when Vernon's sister Marge viciously insults his parents and provokes him to inflate her and float away. Expecting to be expelled from Hogwarts for using magic outside school, Harry runs away but is picked up by the Knight Bus and taken to The Leaky Cauldron, where Minister for Magic Cornelius Fudge assures Harry that he will not face punishment. Upon reuniting with his best friends Ron Weasley and Hermione Granger, Harry learns that Sirius Black, an alleged supporter of Lord Voldemort, has escaped Azkaban prison and is expected to come after Harry.
While journeying to Hogwarts, the Hogwarts Express is boarded by Dementors, ghostly prison guards searching for Black; one of them causes Harry to faint, but the new Defense Against the Dark Arts teacher, Professor Lupin, repels it using a Patronus Charm. At Hogwarts, Headmaster Albus Dumbledore announces that Dementors will patrol the school until Black is captured. Hagrid is appointed as the Care of Magical Creatures teacher, but his first class goes awry when Draco Malfoy provokes a hippogriff named Buckbeak to attack him; as a result, Draco's father has Buckbeak sentenced to death.
Hogwarts is put on high alert when the portrait of The Fat Lady warns that Black is in the castle and attempted to break into Gryffindor Tower. The Dementors attack Harry during a Quidditch match, but he is saved by Dumbledore, although his broomstick is destroyed; Harry's sensitivity to the Dementors prompts him to ask Lupin to teach him the Patronus Charm. Harry, unable to visit Hogsmeade Village without permission from his guardians, attempts to sneak out of the castle but is caught by Fred and George Weasley, who provide him with the Marauder's Map, which shows him a secure passage to Hogsmeade. Above The Three Broomsticks pub, he overhears Professor Minerva McGonagall, pub owner Madam Rosmerta and Fudge discuss how Black is Harry's godfather, divulged the Potters' whereabouts to Voldemort, and murdered their mutual friend Peter Pettigrew; Harry vows to kill Black if they meet.
Harry, Ron, and Hermione witness the execution of Buckbeak, after which a large black dog drags Ron into a hole at the base of the Whomping Willow. Harry and Hermione follow them through an underground passage to the Shrieking Shack, where the dog is revealed to be Black, an Animagus. Lupin appears in the shack, where he is revealed to be an old friend of Black and a werewolf. Lupin and Black reveal that Ron's pet rat, Scabbers, is actually the Animagus form of Pettigrew, who is returned to human form and confesses to having betrayed Harry's parents, framed Black, and faked his own death.
The group heads back to the castle, intending to both exonerate Black, who offers to let Harry live with him instead of the Dursleys, and expose Pettigrew as the real killer, but the full moon causes Lupin to transform into a werewolf; amid the chaos, Pettigrew turns back into a rat and escapes. Black transforms into his animal form and fights off werewolf Lupin, who seriously injures Black. Harry finds Black but the Dementors arrive and brutally attack them both until an unseen person casts a powerful Patronus charm to ward them off.
Harry falls unconscious and awakens in the hospital wing, while Black has been recaptured and, with Pettigrew gone, sentenced to the Dementor's Kiss. With Dumbledore's advice, Harry and Hermione use her Time-Turner to travel back in time and rescue Buckbeak from execution. Harry realizes he had saved himself and Black previously with a Patronus charm and used it to drive the Dementors away. They successfully free Black, who escapes on Buckbeak. Lupin subsequently resigns, Severus Snape having exposed his secret condition as a werewolf. Harry receives a new Firebolt broomstick from Black.