Summary
After witnessing the execution of Buckbeak, Harry, Ron, and Hermione are nearly at a loss for words. Harry wants to run back and comfort Hagrid, but Hermione convinces him that it would only make things worse for Hagrid if they were caught in his cabin. Meanwhile, Ron is trying to wrestle Scabbers back into his pocket, but after being missing for so long, Scabbers cannot be contained. He bites Ron's hand and scuttles away. Ron, disregarding the possibility of being seen, runs after him. By the time he captures Scabbers, he has unwittingly landed himself right at the base of the deadly Whomping Willow, a violent tree that guards a secret passageway to Hogsmeade.
Harry and Hermione set their fears aside and follow Ron to the base of the tree, but just as they're about to pull him away, the large black dog that has been following Harry around bounds out of the trees and pounces on Ron. The dog takes Ron's leg in his jaws and drags him into the passageway under the tree. After a short struggle with the Willow's flailing branches, Harry and Hermione enter the passageway themselves and follow it to the end, where they emerge inside the Shrieking Shack. Ron, his leg broken, huddles in the corner of a dusty, boarded-up room. He tries to warn them but it's too late: Sirius Black is an Animagus, a wizard who is able to transform into an animal. And the animal he transforms into: a big, black dog.
Sirius steps out of the shadows and into the center of the room. When Sirius commends Harry on being so much like his father, Harry cannot contain himself. He tackles Black and releases a maelstrom of punches onto the raggedy fugitive's head and torso. There is clearly more to Sirius's story than Harry knows, but before he can explain, Lupin bursts through the door and disarms Harry and Hermione. After a short and cryptic conversation between Sirius and Lupin, they embrace, much to the outrage of the kids. Harry shouts that he trusted Lupin, and Hermione laments the fact that she's been covering for him for half the semester, covering for the fact that Lupin is a werewolf.
Lupin admits that he is impressed with Hermione's attention to detail, but assures them that his status as a werewolf is no secret amongst the faculty. Dumbledore hired Lupin with full knowledge of his condition, because he had known since Lupin was a student at Hogwarts. In fact, the Shrieking Shack was built for young Lupin; he was led there once a month, during the full moon, to isolate him from other students so he could do no harm. Lupin and Sirius beg the students to give them time to explain, and they do. Sirius explains that while he does blame himself for the Potter's death, he didn't sell them out to Voldemort. He says he would rather have died than betray his best friends. The reason Voldemort knew their location is because Black convinced the Potters to make Peter Pettigrew their secret keeper rather than Black, because Pettigrew was a less conspicuous target. The problem was that Pettigrew had already been secretly feeding Voldemort information for over a year.
Pettigrew was boyhood friends with Lupin, Sirius, and James Potter at Hogwarts. He was one of the creators of the Marauders Map. Moony, Wormtail, Padfoot, and Prongs referred, respectively, to Lupin, Pettigrew, Black, and Potter, and the nicknames corresponded to their Animagi. Lupin was called Moony because he's a werewolf, Sirius was Padfoot because he transforms into a dog, James was Prongs because he transformed into a stag, and Pettigrew was Wormtail because he can transform into a rat. Sirius explains that the reason he was breaking into Hogwarts was not to harm Harry, it was to steal Ron's rat, Scabbers—because Scabbers isn't really a rat, he's a man. And that man is Peter Pettigrew. Sirius explains that it wasn't he who murdered twelve people in a public square all those years ago, it was Pettigrew.
Before the kids can absorb the absurdity of their situation, Snape bursts into the Shack and disarms Lupin and Sirius. Harry, Ron, and Hermione cast a disarming charm at Snape at the same time, knocking him out cold. With Snape out of the way, Lupin and Sirius force "Scabbers" to turn back into his human form, and sure enough, in a matter of seconds, Peter Pettigrew stands before them. Sirius and Lupin are prepared to kill Pettigrew, but Harry stops them, insisting that they take him to the castle and send him to Azkaban. So, they tie up Pettigrew, assuring him that if he turns back into a rat, they will kill him. Sirius suspends Snape's limp, unconscious form to take with them, and the seven of them make their way out of the Shack and back to the Whomping Willow.
When they're all finally out in the open air, the clouds part, and a full moon shines back at them. His transformation happens fast, and within minutes, Lupin is a full-fledged werewolf, howling into the night. Sirius wastes no time changing back into a dog to keep Lupin at bay. Pettigrew, seizing the opportunity, unbinds himself. When Ron tries to stop him, he knocks him out with a curse and then changes back into a rat and escapes. Hermione tends to Ron while Harry runs into the forest to help Sirius; he finds him on his back, Dementors swarming over him. Harry tries with all his might to muster a Patronus, but the number of Dementors is overwhelming, and he loses consciousness. But right before he passes out, he sees a magnificent Patronus being produced across the lake in the form of some majestic quadruped. The wizard behind the Patronus looks incredibly like Harry's father, James.
Harry wakes up in the hospital wing with Hermione and Ron, Madam Pomfrey fussing over them, wheeling in a massive hunk of chocolate to remedy their recent contact with Dementors. From his bed, Harry hears Snape and the Minister of Magic discussing what transpired. Snape tells Fudge that by the time he discovered Sirius and the students, they were unconscious. He conjured hospital beds and whisked them away to the castle. When Snape inquires about the status of Sirius Black, the Minister assures him that he is locked in a high tower and will be receiving a Dementor's kiss momentarily, wherein his soul would be sucked out of his body and destroyed. Harry jolts up and insists that they have the wrong man, but Snape blames his claims on delirium. Madam Pomfrey sends Snape and the Minister away, furious that her hospital wing is being crowded by non-patients. Then, Dumbledore walks in, insisting that he speak to Harry and Hermione. He instructs them to use Hermione's Time-Turner to go back and save Sirius, leaving them with only two clues: the location where Sirius is locked up, and the statement, "If all goes well, you will be able to save more than one innocent life tonight" (393).
Harry still has no idea what Dumbledore is talking about, but Hermione quickly explains that a Time-Turner is a magical tool that allows witches and wizards to revisit the past and experience time again. She has been using one all semester in order to double up on classes. Suddenly, Hermione's contradictory schedule makes total sense. Harry and Hermione go back three hours, right before Buckbeak's execution, and Harry realizes what Dumbledore means by "more than one innocent life." Dumbledore is telling them to save Buckbeak and fly him up to the tower where Sirius will get locked up. So, Harry and Hermione manage to sneak around Hagrid's cabin and lure Buckbeak into the forest. Then, they hang back and watch their past selves crawl into the passage under the Whomping Willow, followed by Snape. They watch Lupin turn into a werewolf, and all the while they stay out of the way, knowing that if they are seen, they could alter the course of history.
Harry confided in Hermione that he thinks he saw his father produce the Patronus that saved him and Sirius. Hermione is unconvinced, but Harry can't resist waiting to see if it was really him. They wait, and wait, and no one is coming to save his past self and Sirius. Sirius's soul is about to be lost forever when Harry steps out from behind the trees and produces the Patronus himself. His Patronus takes the form of a stag, just like his father's Animagus. Harry realizes that it wasn't his father he saw across the lake, but himself. Once Snape transports their unconscious bodies to the castle and Sirius is locked away in a high tower in Professor Flitwick's office, Harry and Hermione fly Buckbeak up to Flitwick's office window and break Sirius free.
Since Pettigrew escaped, Sirius is still a wanted man and a fugitive of the Ministry, so Harry cannot take him up on his offer to live with him instead of the Dursleys. But Harry is just happy that his godfather is alive and well. The school year ends, and everyone does well on their finals. Ron's leg heals up nicely, and he, Harry, and Hermione pack up their bags and board the Hogwarts Express back to London. On the train back, a small owl flies up to their compartment window carrying a letter from Sirius. The letter is a check-in, assuring Harry that he is okay, but still on the run. Sirius reveals that he was the one who sent Harry the Firebolt and encloses a signed permission slip allowing him to go to future Hogsmeade trips. Ron invites Harry and Hermione to join him and his family at the Quidditch World Cup over the summer. Though Harry's future remains uncertain, he feels like with Sirius, he's finally found a real link to his parents and a real sense of family.
Analysis
A prominent theme of this novel is transformation, and nowhere is that theme more clear than in these final chapters. Wormtail, Padfoot, and Prongs devoted four years at Hogwarts to becoming Animagi, or wizards who can transform into animals at will, for the sake of keeping their friend Lupin company while he endured being a werewolf during full moons. It is worth noting that each of their chosen animals carries specific symbolism, the most obvious being Peter Pettigrew's, the rat. Rats are often associated with people who will sell others out to an authority figure either to spare themselves of consequences or for personal gain. Pettigrew had been transforming into a rat since he was a teenager, but eventually, his actions proved him to be a "rat" in the euphemistic sense, after he betrayed his friends and "ratted" them out to Lord Voldemort.
The fact that Sirius transforms into a large, black dog makes sense once we know his whole story. Dogs are thought of as loyal companions, protective of their loved ones—sometimes to a fault. This characterizes Sirius perfectly, especially after we learn that this whole time, he was seeking revenge on Pettigrew on behalf of the Potters. He was willing to kill for justice. Going back to the theme of wrongful convictions, the black dog is portrayed by Trelawney as a dreadful omen of death, and so too is Sirius thought to be capable of wanton murder; but in the end, his nature proves to be different, and his canine traits err on the side of loyal companion over murderous beast.
James Potter turned into a stag, an animal associated with nobility and virility. James Potter is a complicated character because most of what we know about him comes from third-party accounts. Harry's image of his father is one of a handsome young rebel, talented, athletic, and popular among his peers. As far as Harry is concerned, his father died a hero, sacrificing himself in the fight against evil. But Snape paints a different picture of James Potter, one of an arrogant bully who frequently acted only out of self-interest. As far as Snape is concerned, if James performed a noble act, it was also somehow self-serving. Instead of experiencing James first hand, the reader is left with several contradictory accounts with which to form their own opinion of him, but all of the accounts align with the characterization of a stag. With the stag, there is an element of majesty, regality, and uprightness. But then again, stags also have their competitive, macho side. A prominent feature of stags is their antlers, which are used to ram and buck other stags.
And finally, these last chapters confirm that Lupin is, in fact, a werewolf. In many ways, the Potter books are structured like mysteries, and this is especially true for Prisoner of Azkaban. There is a murderer on the loose, and he seems to be doing the impossible: breaking into Hogwarts and bypassing Dementors. There are clues throughout the novel that Lupin has a deadly secret; Snape seems to have compelling evidence that Lupin can't be trusted, but also cares for him through treatment for some kind of unspecified chronic illness. And then finally, Hermione's impossible schedule is questioned by Harry and Ron throughout the novel with no conclusive answer. Like a mystery narrative, Rowling frequently winks at these threads, giving readers a chance to connect them. But in the end, the threads are connected for the reader by the "investigator," in this case, Hermione, and the details are teased out for the benefit of the reader in her dialogue with Lupin in Chapter 17. Lupin asks her how long she's known he was a werewolf, and she replies, "Ages ... since I did Professor Snape's essay." Lupin responds by saying that Snape's entire motive in assigning the essay was to make the students realize he was a werewolf. He says, "He assigned that essay hoping someone would realize what my symptoms meant ... Did you check the lunar chart and realize I was always ill at the full moon? Or did you realize that the Boggart changed into the moon when it saw me?" (346). Rowling relies on dialogue for explication and other important revelations, for example, the revelation that Sirius Black is Harry's godfather through the faculty gossip at the bar of the Three Broomsticks.
