Harry Potter and the Prisoner of Azkaban, thirteen-year-old Harry returns to Hogwarts amid panic over Sirius Black, an escaped convict believed to be hunting him. While learning the Patronus charm to fight off soul-sucking Dementors, Harry discovers Black is actually his innocent godfather, betrayed by Peter Pettigrew—who has been hiding as Ron's rat, Scabbers. Sirius Black breaks out of Azkaban, mistakenly believed to be a loyal supporter of Voldemort who betrayed Harry's parents.