A boy determined to save his dad's failing private detective business enlists the help of his dog and parrot (who both talk) to take down the town's tyrannical tycoon, who wants to stop a mansion from being turned into an animal rescue.

Harry está listo para su tercer año en Hogwarts, pero cuando el terrible Sirius Black escapa de la prisión de Azkaban, el peligro se apodera de él y Harry sabe que, tarde o temprano, Black vendrá a su encuentro.