The Harry Potter epic continues to gather speed as Harry enters his third year at the Hogwarts School for Witchcraft and Wizardry and does battle with the traitor behind his parents' deaths. Besides coping with the usual adversaries - sneering classmate Draco Malfoy, evocatively-named Potions Master Snape - the young wizard-in-training has a new worry with the escape of Sirius Black, murderous minion of archenemy Lord Voldemort, from the magicians' prison of Azkaban.