Summary

Nearing the end of the summer, Aunt Marge, Uncle Vernon's sister, visits the Dursleys. She intimidates Harry Potter & ends up being inflated by magic. Harry gets so upset that he packs his things & runs away. That night, the Knight Bus, a bus for wizards, comes along to take him wherever he wants to go. He decides to go to Diagon Alley & finds his friends, Ron & Hermione there. In Diagon Alley, he discovers a murderer named Sirius Black has escaped & is trying to come after Harry. On the Hogwarts train, Dementors come to look for Sirius & Harry ends up fainting. Professor Lupin fights it off & tells the golden trio that the Dementors are at Hogwarts to protect the students from the murderer on the loose. Throughout the school year, the Dementors wreak chaos in the school & due to this, Professor Lupin teaches how to cast the Patronus Charm to Harry.

Since Harry left the Dursleys early, Harry is not able to take trips to Hogsmeade with the rest of his classmates. Instead, he finds a secret passage way that takes him to Hogsmeade without being seen by using the Marauder's Map. While in Hogsmeade, Harry eavesdrops on a conversation in which Sirius Black is Harry's godfather & who double-crossed Harry's parents. Hermione & Ron fight throughout the year due to Ron thinking that Hermione's cat ate Ron's rat. When in Hagrid's class, Buckbeak the hippogriff hurts Draco & because of this, Buckbeak will be slaughtered. Ron's rat escapes Ron's grasp & Ron gets dragged by a huge black dog. Hermione & Harry chase Ron under the Whomping Willow & they discover Sirius is the black dog. Professor Lupin comes in & mentions that he is a werewolf & that Ron's rat is his old friend Peter Pettigrew. Harry stops Professor Lupin & Sirius from murdering Peter & instead wants to take him to the authorities.

That same night, Professor Lupin changes into a werewolf due to the full moon & attacks the golden trio. Sirius distracts Professor Lupin, but Peter escapes. Dementors come into play & knocks Harry, Lupin, & Sirius out. As they lay in the hospital, they tell Dumbledore what happened & Dumbledore tells Harry & Hermione to use the time-turner to go back in the past of when the horrific night began. As they relive the night once more, they alter some things so that Buckbeak is saved & Sirius escapes with Buckbeak. Hogwarts then resumes like normal until the end of the school year.

The Differences

⊱ In the book, Harry pretends to be Neville Longbottom when Stan Shunpike asks him who he is on the Knight Bus. In the film, Harry decides to remain anonymous. My guess is that Harry does not want to be seen as Harry Potter in case Voldemort comes around asking about him & his whereabouts.

⊱ In the book, there is no mention of Shrunken Heads. However, Shrunken Heads were seen a few times throughout the film. In an interview, J.K Rowling has said that when the film director came up with the idea of talking Shrunken Heads, she felt disappointed that she didn't think to write it into her book herself.

⊱ In the book, there is no mention of a Hogwarts choir. In the film though, Professor Flitwick leads the Hogwarts choir into a song ensemble. Having a Hogwarts choir seems fitting for the film to transition between scenes.

⊱ In the book, Harry originally flies Buckbeak around a paddock in the Forbidden Forest. In the film, Harry rides Buckbeak all around Hogwarts. Having Harry fly around the castle with Buckbeak in the film was such a happy moment & gives a huge bond moment between the two.

⊱ In the book, Parvati Patil's boggart was originally a mummy. However, her boggart is seen as a big snake in the film. No one quite knows why this direction was chosen.

⊱ In the book, the origin story of how the Marauder's Map came to be was mentioned. In the film, the Weasley twins simply just give the map to Harry & continues onward, skipping the origin story. I believe that it would have took too long to explain the map's origin in the film, & so they neglected to mention it at all.

⊱ In the book, Ron & Hermione join in eavesdropping on Cornelius Fudge's conversation. In the film, Harry does this alone. I'm not sure why the film did not include Ron & Hermione in this scene.

⊱ In the book, Sir Cadogan's painting traded places with the Fat Lady's painting for awhile due to Sirius entering the castle. Sir Cadogan kept changing the Gryffindor password. In the film, the students simply sleep in the Great Hall until the teachers search every inch of the castle for Sirius. I do not know why they decided to do this, since a scene with Sir Cadogan's password change would have been quite entertaining.

⊱ In the book, Ron speaks up when Professor Snape bullies Hermione & he ends up in a detention. In the film however, Ron just sits back & agrees with Professor Snape that Hermione is a know-it-all. I find this as an interesting take on Ron's character because in this particular scene, Ron sounds like an arse for letting Professor Snape bully her in that way.

⊱ In the book, Hermione gets annoyed with Draco & slaps him in the face. In the film, Hermione still gets annoyed at Draco, but she punches him instead. It would have been pretty funny to see Hermione slap Draco, so they used a great big punch instead.

⊱ In the book, Ron stands in front of Harry on a broken leg to protect Harry from being murdered. In the film though, Hermione stands to protect Harry. My guess is that the director wanted a stronger female sidekick since Ron was a strong male sidekick in the second film.