How did Harry Potter and the Prisoner of Azkaban end?

Harry, Hermione, and Ron discover that it was Sirius Black who betrayed Harry's parents to Voldemort and that he has escaped from Azkaban prison. They also learn that Sirius is Harry's godfather and that he wants to kill him. Sirius is finally cleared of all charges of killing Harry Potter's parents. Harry learns the truth about his godfather, Sirius Black.

At the end of the book, Harry, Ron, and Hermione return to Hogwarts for their third year.