For twelve long years, the dread fortress of Azkaban held an infamous prisoner named Sirius Black. Convicted of killing thirteen people with a single curse, he was said to be the heir apparent to the Dark Lord, Voldemort. Now he has escaped, leaving only two clues as to where he might be headed: Harry Potter's defeat of You-Know-Who was Black's downfall as well. And the Azkban guards heard Black muttering in his sleep, "He's at Hogwarts...he's at Hogwarts."
Harry Potter isn't safe, not even within the walls of his magical school, surrounded by his friends. Because on top of it all, there may well be a traitor in their midst.
All readers will love the dark arts weaving into this superb book. The dementors and the dark feelings that they bring, freezing all the happiness that was existing. Buckbeak the hippogriff makes a show in Hagrid's first class, biting Malfoy in the process. Professor Lupin is a werewolf who teaches his classes about Grindylows and Boggarts, and I reckon he is one of the best characters, and a terrific teacher.
Harry Potter and the Prisoner of Azkaban must be one of the best in this amazing series, it is truly magical!