"Harry Potter and The Prisoner of Azqaban" by J.K Rowling.

Summary
Harry Potter is about to start his third year at Hogwarts, School of Witchcraft and Wizardry, and can't wait to meet his best friends, Ron and Hermione, again. He lives with his uncle and aunt, who are non-magic people, because evil Lord Voldemort killed his mother and father when Harry was a baby. The rumors say that Voldemort couldn't kill Harry, and lost all his powers while trying to. From then on, Harry Potter became famous in the witches and wizards world, as the boy who destroyed Lord Voldemort.
When he gets to Hogwarts the atmosphere is tense. There's an escaped mass murder…