Harry, Ron and Hermione return for a third term at Hogwarts School of Witchcraft and Wizardry. But Harry's fate, and that of the entire community of wizards, looks bleak when the infamous Sirius Black--convicted of abetting evil Lord Voldemort--escapes from prison. The only clue to where Sirius is headed: The Azkaban guards heard Black muttering in his sleep "He's at Hogwarts." Now, even within the walls of his magical school, Harry may not be safe from a convicted killer.