The third book in the Harry Potter series, Harry Potter and the Prisoner of Azkaban, begins with Harry spending a miserable summer at the Dursleys’ house. After receiving an invitation to attend the Quidditch World Cup with the Weasley family, Harry eagerly escapes the Dursleys and enjoys a magical time at the event. However, the World Cup is marred by an attack from followers of Lord Voldemort, known as Death Eaters, which disrupts the celebration and leaves Harry troubled.
Back at Hogwarts for his third year, Harry discovers that a dangerous criminal, Sirius Black, has escaped from Azkaban, the wizarding prison. Black was convicted for betraying Harry’s parents to Voldemort, leading to their deaths, and is believed to be after Harry. The school is placed under heightened security, with the terrifying Dementors, Azkaban guards, stationed around the school to protect students from Black.
During the first few months of the school year, Harry experiences strange, unsettling encounters with the Dementors. Their mere presence causes Harry to faint and relive the traumatic night of his parents’ death, which leaves him vulnerable and increasingly frightened. He also learns about the importance of Patronus magic, a powerful defensive charm that can repel Dementors.
Harry’s main focus during his third year, however, is the mystery surrounding Sirius Black. He, along with his friends Ron Weasley and Hermione Granger, begins to uncover the truth about Sirius’ escape. They also become more suspicious of Remus Lupin, the new Defense Against the Dark Arts teacher, who seems to be hiding a secret.
The trio also learns more about the Marauder’s Map, a magical map of Hogwarts that reveals the entire school, including the movements of people. Harry, Ron, and Hermione use it to sneak into places they shouldn’t be and discover more about the past of their families. It’s through the map that Harry learns of Peter Pettigrew, a former friend of his parents who betrayed them, and who is thought to be dead. The map shows that Pettigrew is alive and living as Ron’s pet rat, Scabbers.
As the plot unravels, it’s revealed that Sirius Black is not the villain everyone believes him to be. In fact, Sirius was framed for the crime by his best friend, Peter Pettigrew, who had actually betrayed Harry’s parents to Voldemort. Pettigrew faked his own death and has been hiding in plain sight as Scabbers, Ron’s pet rat, for many years.
With the truth now known, Harry, Ron, and Hermione work together to save Sirius from being recaptured by the Dementors. They are aided by Hermione’s use of a time-turner, a magical device that allows her to travel back in time. This enables them to witness key events that had occurred earlier in the day, ultimately helping them rescue both Sirius and Buckbeak, a magical hippogriff who was sentenced to death after an incident with Draco Malfoy.
In a dramatic climax, Harry and Hermione manage to prevent Sirius’ capture, allowing him to escape on Buckbeak’s back. They also ensure that Pettigrew’s escape is prevented, but they are unable to expose his true identity to the wizarding world. In the end, Sirius sends Harry a message, asking him to meet him if he ever needs a godfather.
The book ends with Harry returning to the Dursleys for the summer, now knowing that he has a connection to a living relative, Sirius Black, and that the truth about his parents’ deaths is much more complicated than he had been told. The story is full of twists and reveals, and it marks a significant turning point in the series as Harry begins to learn more about his past and his parents’ lives.