Harry Potter and the Prisoner of Azkaban

Sirius Black breaks out of Azkaban, and everyone says he's after Harry. Dementors start guarding Hogwarts, and the new teacher, Remus Lupin, teaches Harry to cast a Patronus. Harry learns that Black supposedly betrayed his parents. In the Shrieking Shack, Lupin and Black tell the truth: the traitor was Peter Pettigrew, hiding for years as Scabbers, Ron's rat. The full moon turns Lupin into a werewolf, and Pettigrew escapes. Black is captured. With Hermione's Time-Turner, she and Harry go back a few hours, save Buckbeak the hippogriff, and free Sirius, who flies away. Harry drives off the dementors with a stag Patronus. Left open: Pettigrew is on the loose and Sirius is still a fugitive.

• After the credits Not a scene: the credits roll over the Marauder's Map, with footprints walking the corridors. At the very end, Harry says "Mischief managed," then "Nox," and the screen goes dark.

1. Behind the scenesMichael Gambon takes over Dumbledore

   After Richard Harris died, Michael Gambon took over as Dumbledore starting with this film, playing a looser, less solemn version of the headmaster.

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2. Behind the scenesCuarón's homework

   Alfonso Cuarón asked the trio to write an essay about their characters. Emma Watson turned in 10 pages, Daniel Radcliffe exactly two, and Rupert Grint didn't turn one in.

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3. ReferenceShakespeare in the choir

   "Double Trouble," the song the frog-holding choir sings at the start of term, takes its lyrics from Shakespeare's Macbeth.

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4. SetupTrelawney's real prophecy

   At the end of the year, Professor Trelawney goes into a trance and says the Dark Lord's servant will return to his master. She's right, and it matters later.

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