Which J.K. Rowling novel follows Harry Potter’s third year at Hogwarts and introduces Sirius Black?

Harry Potter and the Prisoner of Azkaban follows Harry Potter’s third year at Hogwarts and introduces Sirius Black.

Published in 1999, the third novel begins with news that Sirius Black has escaped from Azkaban. The wizarding authorities initially describe him as a dangerous mass murderer connected to Lord Voldemort, so Hogwarts is guarded by Dementors during the school year.

As the plot develops, Harry learns that the official story is incomplete. Sirius is revealed to be his godfather, while Peter Pettigrew—not Sirius—was responsible for betraying Harry’s parents to Voldemort. The novel also introduces Remus Lupin as the new Defence Against the Dark Arts teacher.

The book is notable for shifting the series toward a more complex treatment of memory, betrayal, and family history. Its film adaptation, directed by Alfonso Cuarón, was released in 2004 and starred Gary Oldman as Sirius Black.