Harry Potter and the Prisoner of Askaban is the third book of the Harry Potter collection. In this book Harry Potter, who is soon to be 13 is now in his third year in Hogwarts School. Aunt Marge comes to stay with the Dursleys, and she insults Harry's parents a numbers of times. Harry then accidentally causes her to inflate, like a big balloon and floats away. Harry then runs away and leaves the Dursley's home, which the Knight Bus then picks him up. Harry eventually gets to school and the word around is that Sirus Black whom escaped from jail is out to get Harry. Harry is then scared and at the same time curious to find out who is this Sirus Black and why is it that he is out to get him? With this question wandering and his head Harry does allot of investigations Harry finds out some of the truth about Sirus Black. He finds out that Black is his godfather and that he the one who sold out Harry's parent to Voldmort. But if he is Harry godfather why do that. Wanting to know more Harry then goes out to find Black. Finally he meets Sirus for his first time face to face in the Willow Tree outside the school. Harry, with eager of getting revenge and his friend then tries to attack Sirus black. Then comes Lupin who is a werewolf that is able to stay human because of the potion that he must continually take in order to stay human. He then stops the 3 kids. Eventually when they are able to calm down and listen to Sirus and Lupin explain everything. They explain how Snape once followed Lupin toward his transformation site in a practical joke set up by Sirius, and was rescued by James Potter. At this point, Professor Snape reveals himself from underneath Harry's invisibility cloak, but Harry, Ron, and Hermione disarm him.
Lupin and Black then explain that the real murderer of Harry's parents is not Black, but Peter Pettigrew, who has been heard to have been dead but really hidden all these years disguised as Scabbers, Ron Pet rat. Lupin transforms Scabbers into Pettigrew, revealing himself to be Voldemort's servant, and Black to be innocent. They all travel back to Hogwarts, but at the sight of the full moon, Lupin, who has forgotten to take his controlling potion, turns into a werewolf. Sirius Black responds by turning into the large black dog in order to protect Harry, Ron, and Hermione from Lupin. As Black returns from driving the werewolf into the woods. Then Sirus black weaken then falls on the floor near the lake. A Dementors approaches, and Black is then paralyzed and knocked out. One of the Dementors sucks the soul out of Harry. Then out of somewhere comes a patronus that drives the Dementors away. Harry wakes up in the morning in the hospital wing. He is eager to know what is going on and what is going to happen to his godfather Sirus Black now that he was found. Harry tells the headmaster of the school that Black is innocent. Dumbledore believing Harry and his friend then gives Harry and Hermonine a special item that can go back in time. He tells them that if they are successful they may save more then two life. So Harry and Hermonie goes back to time to not only save Sirus but also Buck beak. When they return to the school they then say their goodbyes to Sirus Black and he flies away on buck beak. The next day Harry say his goodbyes to his friends and they all go home.