Harry Potter, along with his friends, Ron and Hermione, are about to start their third year at Hogwarts School of Witchcraft and Wizardry.

Harry can't wait to get back to school after the summer holidays. (Who wouldn't if they lived with the Dursleys?) But when Harry gets to Hogwarts, the atmosphere is tense.

There's an escaped mass murderer on the loose, and the sinister prison guards of Azkaban have been called in to guard the school.