Harry Potter and the Prisoner of Azkaban is the third book is J. K. Rowling's proposed seven volume Harry Potter series. This book marks a distinct change in Rowling's writing style. Harry is growing up, and Rowling's style is maturing likewise. Her plotting has become tighter, and the story more complicated. As the book opens, Harry is thirteen, and he is once again, spending his summer vacation with his Aunt and Uncle, the Dursley's.
Per usual, the Dursley's are treating Harry horribly, and things only get worse when his uncle's sister, Marge, shows up. She is even meaner to Harry than the Dursley's and she pushes Harry past his limits of endurance. In a fit of rage he casts a spell upon her that causes her to swell to an enormous size, and like a balloon, she takes flight, and so does Harry. In a flash, Harry grabs his meager belongings and runs away into the dark night. (Don't worry about Marge. Employees of the 'Accidental Magic Reversal Department' quickly set her back to rights.)
Unbeknownst to Harry, Sirius Black, one of Lord Voldemort's minions, has escaped from Azkaban. Azkaban is a sinister prison that is used to house rouge wizards. The prisoners are guarded by Dementors, beings that feed of the emotions of others. Most prisoners go insane within a matter of days, but not Sirius. Now, everyone fears that Sirius has escaped for one purpose and one purpose only, to kill Harry.
In this tale, Harry begins to learn more about his parents and how they died. Since the first novel, Harry has known that his parents were killed by the evil wizard Voldemort, but he had not known all the particulars. In this novel, he learns more than he really wants to know, to the point of hearing his mother's screams! There are a few parts in this novel that some younger children may find unsettling, but on the whole they'll love this book.
His third year at Hogwarts School of Witchcraft and Wizardry begins like those that came before. Harry becomes reacquainted with old friends, and old enemies. However, unlike the previous years, Harry's movements are now greatly circumscribed because everyone fears that Sirius will show up at any moment to do away with Harry. It does not help much that Professor Trelawney, Harry's Divination teacher, keeps predicting that he is going to die. Worse, for Harry, is that he is not even allowed to walk the school grounds at night, or go into the nearby Wizards' town of Hogsmeade. This is a treat that Harry had been looking forward to fondly, as you must be a third year student before you are allowed to visit the town. Nonetheless, Harry being a normal kid, he does manage to sneak into the town by making use of some secret tunnels and his father's old invisibility cloak.
In Harry Potter and the Prisoner of Azkaban, Rowling's has crafted a straightforward mystery. She asks the question, "Who betrayed Harry's parents to Voldemort?" and than has Harry solve the mystery. This is an edge of your seat thrill ride that will have you holding your breath as you hungrily turn the pages, so that you can learn, along with Harry, who the traitor was.