Harry Potter and the Prisoner of Azkaban
Sirius Black, an alleged mass murderer escapes from the wizarding prison, Azkaban. After Harry manages to inflate his Aunt Marge, his aunt and uncle kick him up and he takes the Knight Bus to the Leaky Cauldron, a pub on Diagon Alley, where he spends the rest of the summer. Dementors, who guard Azkaban, are stationed around Hogwarts as it is believed that Sirius wants to kill Harry. Harry finds a friend in Professor Lupin, his third Defence Against The Dark Arts teacher, and Lupin helps Harry create a Patronus to get rid of the Dementors, as they make those close to them relive their worst memories. During a Quidditch match where Dementors storm the grounds, Harry falls off his broom and it is crushed by the Whomping Willow. He later receives a brand new broom in the mail, a Firebolt, from an anonymous person. Fred and George give Harry the Marauders Map to sneak to Hogsmeade, a nearby town that Harry cannot visit because his Aunt and Uncle did not sign his permission slip. Sirius, who turns out to be Harry’s godfather and has been wrongly accused, has actually come to Hogwarts to find and kill Peter Pettigrew who is parading as Ron’s rat Scabbers, because it was he who committed the crimes Sirius was convicted of and he was the one who sold Lily and James Potter to Lord Voldemort. Harry and Hermione help Sirius escape the Dementors after using the Time-Turner device that Professor McGonagall gave her at the start of the year to attend multiple classes at the same time.
What the movie doesn’t tell you:
The Whomping Willow (that Ron and Harry fly the car into in the previous film) was actually planted when Lupin came to the school to hide the secret entrance to the Shrieking Shack so that Lupin could go there during the full moon. James Potter, Sirius Black and Peter Pettigrew also learn to be animagus’s to keep Lupin company during the full moon in the Shrieking Shack. The film also leaves out that Lupin, Sirius, James and Peter were the creators of the Marauder’s Map. They also leave out how far Harry goes in to memory when in the presence of Dementors, he hears his parents try to fight Voldemort before they die; it’s the only time he hears his parents voice and he secretly cherishes the connection. The film also doesn’t detail how Sirius escapes from Azkaban. Also, Cedric Diggory makes his first appearance in this book, as does Cho Chang.