Here you will find a Harry Potter and the Prisoner of Azkaban summary (J.K. Rowling's book).
We begin with a summary of the entire book, and then you can read each individual chapter's summary by visiting the links on the "Chapters" section.
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On the eve of his thirteenth birthday, Harry Potter receives presents from his school friends through Owl Post. The following day, news breaks of a prison escapee named Black, just as Aunt Marge arrives for a visit. After an argument results in Harry unintentionally inflating her, he runs away, encountering a large, ominous black dog before being picked up by the Knight Bus. Once in Diagon Alley, he's introduced to Cornelius Fudge, the Minister of Magic, and reunites with his friends Ron and Hermione. Hermione acquires a cat named Crookshanks, who relentlessly pursues Ron's old rat, Scabbers. Before heading to Hogwarts School, Harry overhears a conversation revealing that the escaped prisoner, Sirius Black, is targeting him. Once at Hogwarts, Harry experiences fainting spells due to the chilling presence of Dementors, entities tasked with recapturing Black. Professor Lupin, the new Defense Against the Dark Arts teacher, revives him. In Divination class, a prophecy of Harry's death is made after the symbol of a Grim, a large black dog signifying death, is spotted. Meanwhile, a Hippogriff named Buckbeak injures Malfoy, causing a fiasco that threatens Hagrid, the creature's caretaker, with job loss, and Buckbeak with death. During a tea with Lupin, Harry learns the reason he wasn't allowed to face a Boggart, a creature embodying one's greatest fear, in class was due to Lupin's concern that it would morph into Voldemort. Soon after, Black infiltrates Hogwarts and destroys the portrait protecting Gryffindor Tower. With the assistance of the Marauder's Map provided by the Weasley twins, Harry secretly enters Hogsmeade, where he learns of Black's involvement in his parents' death. After a series of events, including receiving a suspiciously sent Firebolt broomstick and reconciling with his friends, Harry, Ron, and Hermione confront Black in the Shrieking Shack. They discover Lupin's werewolf nature and that Black is innocent. Instead, Peter Pettigrew, who had been hiding as Scabbers the rat, is the real traitor. Lupin's transformation into a werewolf amidst the full moon leads to chaos, with Black assuming his dog form to protect the children, and Harry being saved from the Dementors by a Patronus charm. Dumbledore later advises Harry and Hermione to use a time-turner to rescue both Black and Buckbeak. After successfully doing so and losing Lupin as a professor, Harry receives a letter from Black, lifting his spirits as he heads back to the Dursleys for the summer.
The tale commences at midnight, with Harry Potter quietly working on a witch-burning essay for Hogwarts, trying not to disturb his sleeping relatives. He notices it's one o'clock, marking his thirteenth birthday, a day his relatives, the Dursleys, never acknowledge. Harry reflects on his parents' tragic demise by Lord Voldemort, and his own near-death experience with the dark lord. Despite it all, he feels a sense of relief now that he's thirteen. Suddenly, Harry spots strange flapping objects approaching his window. The objects turn out to be three owls, one being his own Hedwig, the other an unfamiliar one, and the third, Errol, Ron Weasley's own weak owl. They bring birthday gifts and cards from his best friends, Ron, Hermione, and Hagrid. Ron gifts him a pocket Sneakoscope and shares news about a family trip to Egypt. Hermione gives him a Broomstick Servicing Kit, which he values due to his love for Quidditch, a broomstick sport. Hagrid gifts him a textbook, "The Monster Book of Monsters." Harry also gets a letter from Hogwarts requesting guardian permission for students to visit Hogsmeade, a wizarding village. Knowing he won't get the Dursleys' approval, Harry disregards it. Yet, relooking at his birthday cards and gifts, he falls asleep feeling his birthday was meaningful for the first time.
Harry joins his cousin Dudley, Uncle Vernon, and Aunt Petunia for breakfast where they are engrossed in a news story about an escapee named Black. The family continues their usual behavior of disregarding Harry. Vernon leaves to retrieve his sister, Aunt Marge, cautioning Harry to act "normal." Harry is displeased as Marge often brings her menacing dogs and constantly belittles him. However, Harry sees an opportunity and strikes a deal with Vernon - he will pretend to be "normal" and fabricate attending a school for dangerous boys in exchange for Vernon signing his Hogsmeade form. Vernon reluctantly agrees. Aunt Marge shows up, lavishing Dudley with compliments, feeding her dog Ripper tea, and questioning Harry about his school. Harry answers as tactfully as possible but grows increasingly agitated when Marge insults his parents. Marge comments on his mother, "If there is something wrong with the bitch, there'll be something wrong with the pup," which angers Harry so much that he unintentionally breaks her wine glass. From then on, Harry is even more on guard. Eventually, during a dinner, Marge casually mentions Harry's parents died irresponsibly in a car accident, causing Harry to lose his temper. Harry's anger results in Marge swelling up and floating. Amid the ensuing chaos, Harry gathers his belongings, threatens Vernon with his wand, and leaves.
Harry, unsure of his next steps after leaving the Dursleys, contemplates living as a wizard in London, fearing expulsion from Hogwarts for practicing magic outside school. Sensing he's being watched, he is startled by the sight of a large threatening creature. After falling into a gutter, he is saved by the Knight Bus, an emergency transport for distressed wizards. Harry, hiding his identity, introduces himself as Neville Longbottom and boards the bus. The magical bus zips through the city, with obstacles moving out of its path. On the ride, Harry learns about Sirius Black, a supporter of Voldemort, who is on the run after escaping Azkaban. Black was imprisoned for murdering thirteen individuals with one curse. The bus drops him off at Diagon Alley, a wizarding district in London. He is met by Cornelius Fudge, the Minister of Magic, who discloses Harry's true identity to the curious bus crew. Fudge, appearing strangely relieved to see Harry unharmed, invites him for dinner. Harry is puzzled by Fudge's lack of concern over his misconduct with his aunt, who has now returned to her regular size. Brushing off his doubts, Harry retires to a room in the Leaky Cauldron, arranged by Fudge, where he can stay until school resumes.
Over the following weeks, Harry blissfully explores Diagon Alley. He completes his schoolwork, enjoys ice cream in outdoor cafes, gazes at a Firebolt broomstick displayed in a Quidditch shop and purchases his school textbooks. In the bookshop, he is unnerved to see a large black canine on a book cover, it reminds him of a shadowy figure he noticed when he left the Dursleys. He eventually meets up with Ron and Hermione, and during their chitchat about their holidays and upcoming classes, they visit a pet shop. Ron purchases tonic for his frail rat, Scabbers, but an orange cat lunges at them, chasing after Scabbers. Ron is livid when Hermione gets the cat, named Crookshanks. The trio meet up with the Weasleys, where all of Ron's siblings are in their comfort zones. The twins, Fred and George, are keeping everyone entertained. Percy is acting intolerably irritated, while Ginny, the youngest and only female Weasley, is giggling timidly. They share a meal, after which Harry overhears Mr. and Mrs. Weasley arguing about whether to inform Harry of Sirius Black's escape from Azkaban with the apparent goal of murdering him. Harry doesn't feel overly scared; he believes Hogwarts is very secure, plus he has faced Voldemort twice already.
The next day, Harry, Ron, Hermione, and the Weasleys get a ride to King's Cross Station in Ministry of Magic cars, which is not the norm. They head to platform nine-and-three-quarters and board the Hogwarts Express to school. Before departing, Mr. Weasley warns Harry to avoid Black. On board, Harry shares Black's story with Ron and Hermione, while a ragged man named R.J. Lupin sleeps nearby. They then discuss Hogsmeade, making Harry upset since he can't join. During the journey, Crookshanks targets Scabbers, and Draco Malfoy teases Ron about his family's financial state. However, the presence of a sleeping Lupin silences Malfoy. Suddenly, the train halts and lights go off. A tall, robe-clad creature, a Dementor, enters their compartment and Harry passes out from an unbearable cold feeling, hearing screams. When he comes to, he learns Lupin dispatched the Dementor by sending a silver object its way and that Dementors are Azkaban guards. Lupin offers chocolate to everyone, and they shortly reach Hogwarts. At Hogwarts, Professor McGonagall checks on Harry due to his reaction to the Dementor and then privately talks with Hermione. Harry and Hermione join the others in the Great Hall, where Dumbledore, the headmaster, reluctantly reveals that Dementors will guard the castle entrances due to Black's threat. He also announces Lupin as the new defense against the dark arts teacher, and Hagrid as the care of magical creatures teacher. The feast begins and Harry feels happy to be back at Hogwarts.
At the morning meal, Harry, Ron and Hermione brush off Malfoy's jibes about the Dementor incident. Hermione's packed schedule, with three simultaneous nine o'clock classes, sparks intrigue, but she avoids explaining. The trio navigate a labyrinthine route to the Divination class, guided by a stout, combative knight named Sir Cadogan. In the Divination class, Professor Trelawney shifts from nebulous future predictions to tea-leaf-reading lessons. Ron and Harry's attempts at divination turn into jest before Professor Trelawney discovers a Grim, a death-omen dog figure, in Harry's cup. Hermione, skeptical of the whole affair, dismisses it, but the rest of the class is unnerved. They later attend Transformation class, where Professor McGonagall comforts Harry, revealing that Trelawney's annual death predictions have never been accurate. Their following lesson, Care of Magical Creatures, introduces them to Hippogriffs, mythical half-horse, half-eagle creatures. Harry successfully interacts with one called Buckbeak, managing to ride it. But when Malfoy provokes Buckbeak, he's attacked and injured. Hagrid rushes the injured Malfoy to the Infirmary. Harry worries about Malfoy exploiting the situation to jeopardize Hagrid's job. In the evening, they find Hagrid drunk and upset. He suddenly warns Harry against night-time wanderings and escorts them all back to the castle.
Malfoy, with a dramatically wrapped arm, comes back to class a few days later. As the others work in Potions class with Snape, Malfoy gossips about his father's sway over Hagrid's job. Malfoy's words about seeking revenge on Sirius Black leave Harry both angry and puzzled. Snape's teaching style remains consistent, berating Neville for misunderstanding potion instructions, and Hermione for assisting Neville. On their way to Defense Against the Dark Arts class, Hermione mysteriously vanishes, only to be spotted rushing up the stairs behind them. Professor Lupin introduces the class to a Boggart hiding in a wardrobe. As they enter the classroom, Snape throws a nasty remark towards Neville. Lupin, however, asks Neville to be the first one to take on the Boggart. Despite his fear, Neville executes the "Riddikulus" spell, turning the Boggart from his worst fear into a laughing matter. Each student has a go, transforming their fears into hilarity. When Lupin confronts the Boggart, it morphs into an orb, and for Ron, it's a massive spider. The class overcomes the Boggart, though Harry doesn't get a shot.
Everyone starts loving defense against the dark arts class, with the exception of Malfoy who spends his time criticizing Professor Lupin's shabby clothes. The Gryffindor Quidditch team begin training, aiming to win the cup. As Halloween draws closer, marking the first Hogsmeade trip, Harry feels upset he can't join. His friends assure him they'll bring back a bunch of sweets. Despite their continuous squabbles about their pets, Ron and Hermione sympathize with Harry. One such argument arises when Crookshanks attacks Scabbers once again. During the Hogsmeade trip, Harry has tea with Professor Lupin. Harry questions why he wasn't allowed to fight the Boggart, to which Lupin confesses his fear of Voldemort appearing in class. Harry admits his fear was actually about the Dementors. Lupin then remarks, "That suggests that what you fear most of all is fear. Very wise, Harry." Their conversation is interrupted by Snape delivering a hot goblet to Lupin, who drinks it immediately. Snape's actions make Harry suspicious that he may be attempting to poison Lupin to take over his job, but Lupin doesn't seem worried. Post Hogsmeade, Ron and Hermione gift Harry a bag full of sweets. He shares with them his doubts about Snape and Lupin. After the Halloween feast, their return to Gryffindor Tower is met with a shocking sight: the slashed portrait of the Fat Lady who is nowhere to be found. Amidst the chaos, Peeves the Poltergeist cackles as he breaks the news that Sirius Black attacked the portrait.
Following the invasion by Black, students are relocated to the Great Hall for the night as teachers, under Dumbledore's supervision, scour the castle for any traces of Black, but to no avail. The Fat Lady's portrait is replaced by Sir Cadogan, who spends his time creating complex passwords and proposing duels to students. As the weather deteriorates, Gryffindor House prepares for a game against Hufflepuff. Despite Hufflepuff's reputation as a less challenging opponent, Oliver Wood, the Gryffindor captain, urges his team not to underestimate them. On the day of the game, Snape, who is stepping in for Lupin, discards the original Defense Against the Dark Arts lesson plan and instead instructs the class on werewolves. During the match, visibility is poor due to the lashing rain and wind. Harry and Hufflepuff's seeker, Cedric Diggory, are on the lookout for the Snitch with no success. Suddenly, Harry spots a large black dog against the bleachers and then the Snitch. As he chases the Snitch on his Nimbus 2000, he sees scores of Dementors at the side of the field. Overwhelmed by a chilling sensation and haunted by the sound of his mother's scream, he plummets from the sky. When he regains consciousness in the infirmary, he learns that Cedric secured the Snitch, giving Hufflepuff the victory. He also discovers that his Nimbus was destroyed by the Whomping Willow, a ruthless tree in the Forbidden Forest.
Following his broomstick accident, Harry is despondent, distressed by his recurring encounters with the Dementors and his sightings of the Grimm. When Lupin resumes teaching, he relieves the students from Snape's excess werewolf homework and clarifies to Harry that the Dementors affect him severely due to his traumatic past. He further explains that these creatures thrive on human despair. Lupin reassures Harry that he will teach him a spell to counter the Dementors after Christmas, which raises Harry's spirits. During a second trip to Hogsmeade, Harry meets Fred and George Weasley who secretly give him a magical map, The Marauder's Map, which reveals all areas and people of Hogwarts. The map, only visible when tapped and activated with the words "I solemnly swear that I am up to no good," bears the signatures of Padfoot, Prongs, Moony, and Wormtail. Using the map, Harry sneaks under the school into Honeydukes sweetshop in Hogsmeade, where he meets Ron and Hermione. Despite Ron's joy at seeing Harry, Hermione expresses fear that Black might find Harry, or discover the tunnels. They then visit the Three Broomsticks Pub, enjoying hot butterbeer served by Madam Rosmerta. Suddenly, Cornelius Fudge and several Hogwarts teachers, including Hagrid, McGonagall, and Flitwick enter the pub. Harry hides and overhears them discussing Black's history of treachery. They reveal Black was responsible for betraying Harry's parents to Voldemort, resulting in their deaths. Fudge explains that Black had been the Secret-Keeper for Harry's parents, who betrayed their location to Voldemort. These revelations attribute the death of Lily and James Potter directly to Black.
Harry is upset after eavesdropping and is filled with rage towards Sirius Black. His friends, Ron and Hermione, dissuade him from any dangerous actions like seeking revenge on Black. Distracting him, they all visit Hagrid, who's distraught as his hippogriff, Buckbeak, is facing a trial for attacking Malfoy and could potentially be executed. They all try to console Hagrid and later head to the library to look into past cases where magical creatures were spared, but their search is fruitless. On Christmas, Harry discovers a Firebolt broomstick among his gifts. Despite no identification, he's delighted. However, Hermione is suspicious and after Christmas lunch, where Professor Trelawney foresees more deaths, she informs Professor McGonagall about the broomstick. McGonagall confiscates it that night for inspection, suspecting Sirius Black might be involved. This infuriates Ron and Harry with Hermione.
School is back in session and Oliver Wood attempts to convince Professor McGonagall to return Harry's Firebolt. Meanwhile, Harry receives private lessons from Lupin to master the Patronus spell, designed to protect against Dementors. To successfully cast it, Harry must concentrate on a happy memory while saying "Expecto Patronum" to repel the Boggart, disguised as a Dementor. Harry practices with several joyful memories, but only gains minor success. Lupin always ends the sessions by offering Harry chocolate. Harry, however, suspects his inability to fully cast the Patronus spell is due to his hidden desire to hear his parents' voices, which he hears during Dementor attacks. As time continues, Hermione remains swamped with her studies. Wood comes back unsuccessful from his meeting with Professor McGonagall, failing to retrieve the broomstick. Harry, during another session with Lupin, learns about the haunting "kiss" of the Dementors, an act that sucks the soul out of a person. Lupin reveals the Ministry of Magic has allowed the Dementors to give this "kiss" to Sirius Black if they capture him. Shaken by this new knowledge, Harry encounters Professor McGonagall, who finally hands over the Firebolt. The Gryffindor common room buzzes with excitement over Harry's broomstick, even drawing Hermione's attention away from her books. The joy is short-lived when Ron announces his pet rat, Scabbers, is missing, with his bed showing traces of blood and orange cat hairs.
Tensions are sky-high between Ron and Hermione due to the apparent demise of Scabbers, supposedly caused by Crookshanks. To uplift Ron's spirits, Harry invites him for a Firebolt ride post their Quidditch practice, and Ron gladly agrees. The Gryffindor team is in full gear for their match against Ravenclaw. Harry's increasing mastery of the Firebolt elevates the team's spirits and the chances of winning the game look promising. The anticipation for the game is palpable among everyone, including Oliver Wood, Percy Weasley, and his girlfriend Penelope. As the game starts, Lee Jordan, the commentator, is so engrossed in Harry's new broomstick that he misses narrating the game's key plays. Harry's opposing seeker is Cho Chang, a charming and sporty fourth-year Ravenclaw student whom Harry appears to be developing feelings for. Harry's chivalric nature irks Oliver Wood, who reprimands him for not giving priority to the Snitch over Cho. Harry spots the Snitch during the game, but his focus shifts towards three apparent Dementors on the sideline. Instinctively, he casts a Patronus towards them, allowing him to catch the Snitch effortlessly and secure a victory. Only later does he find out that the Dementors were Slytherins, including Malfoy, disguised in cloaks to disconcert Harry. McGonagall penalizes them harshly to everyone's satisfaction. The victorious team and their friends spend the rest of their day and night celebrating in the Gryffindor common room. However, their joy is short-lived when Ron wakes up screaming before dawn, claiming that Sirius Black had slashed his bed's curtain. The panic escalates when Sir Cadogan confirms letting an intruder into Gryffindor Tower, as they possessed all the passwords written on a piece of paper. It is later revealed that Neville Longbottom had accidentally misplaced this slip of paper in a corridor.
Following an additional intrusion from Black, Hogwarts heightens its security. Black's face is programmed into door enchantments, the Fat Lady's portrait is accompanied by troll guards, and Neville is denied the Gryffindor password. Harry and Ron are invited to tea with Hagrid one afternoon, where he admonishes them for ignoring Hermione, as she is miserable without their companionship. "I thought you two'd value yer friend more'n broomsticks or rats," he says. During another Hogsmeade visit, Harry, cloaked in invisibility, joins Ron in exploring the Shrieking Shack, Britain's most haunted house. Malfoy, Crabbe, and Goyle mock Ron, leading to Harry flinging mud at them from under his cloak, amusing himself and Ron until his cloak slips off, revealing his head. Malfoy reports this to Snape and Harry manages to hide his cloak just on time as Snape takes him to his office. There, Snape criticizes Harry's misbehavior and compares him to his arrogant father. Harry lashes out at Snape, who in return, demands him to turn out his pockets, discovering the map. The map insults Snape instead of revealing its secrets. Snape calls Lupin through the fireplace, who dismisses the map as a harmless joke-shop toy. Ron vouches for its innocence, forcing Snape to let them go. However, Lupin reprimands them for owning the map, considering Black's escape, suggesting that the map creators might be trying to entice them out of the castle. "Your parents gave their lives to keep you alive, Harry," he says. "A poor way to repay them—gambling their sacrifice for a bag of magic tricks." On their way out, Hermione confronts them with the news that Buckbeak lost his case and is to be executed.
Harry, Ron, and Hermione read Hagrid's letter about Buckbeak's fate, leading to Hermione reconciling with Ron for Scabbers's demise. Hagrid tearfully discusses Buckbeak's situation in the next magical creatures class, during which Hermione hits Malfoy for mocking Hagrid. Later, Harry and Ron find an overworked Hermione sleeping in the common room. She arrives late to Divination class, dismissing Professor Trelawney's repeated Grim predictions, and unexpectedly walks out. As final exams and the decisive Quidditch match draw near, the pressure mounts; if Gryffindor is to win the Cup, they must beat Slytherin by a minimum of 200 points. Haunted by nightmares, Harry glimpses the big black dog again, but it vanishes before Ron can see it. Despite Slytherin's typical foul play, the Quidditch match proves no challenge for Harry and his Firebolt. He and Malfoy spot the Snitch, triggering a race that Harry wins, securing both the game and the Quidditch Cup. The team celebrates in tears and joy. The chapter ends with Harry musing that his current euphoria could produce a mighty Patronus.
Following the successful Quidditch match, the students are swamped with final exams. Hagrid's magical creatures exam is a breeze, due to his decision to only teach harmless creatures after the last accident. Harry performs exceptionally well in the defense against the dark arts exam, battling various creatures learned throughout the semester. During Divination, Professor Trelawney instructs Harry to predict the future using a crystal ball. Suddenly, Trelawney, in a trance-like state, foretells that the Dark Lord's servant will return to him that night. She quickly snaps back to reality with no memory of her prediction. Harry rushes off to share the news with Ron, only to learn that Buckbeak's appeal has been denied and the hippogriff will be executed at dusk. Harry, Ron, and Hermione decide to console Hagrid, with Hermione secretly fetching Harry's invisibility cloak en route. They encounter a shaken Hagrid who believes Lucius Malfoy must have intimidated the Committee for Disposal of Dangerous Creatures. In the midst of their visit, Hagrid accidentally spills a milk jug. Hermione, while attempting to refill it, stumbles upon Scabbers hiding inside. Ron manages to grab the frantic rat, but before they can discuss it further, the executioners arrive. Hagrid hastily ushers the trio out of his cabin, covered by the invisibility cloak. As they retreat, the ominous sound of an axe rings out.
Harry, Hermione, and Ron depart from Hagrid's cabin and encounter difficulties staying cloaked due to Scabbers' constant squirming. Harry soon discovers that Scabbers' nervousness is due to the presence of Crookshanks and a large black dog. This dog startles Harry, attacks Ron, and drags him into the Forbidden Forest. Harry and Hermione follow them into the Whomping Willow, where Ron is dragged into a hidden path by Crookshanks pressing a secret knot in the tree. The path leads them into the notorious Shrieking Shack in Hogsmeade. They find Ron in the company of Crookshanks and Sirius Black, who had transformed from the black dog. Sirius disarms Harry and Hermione, leading to a scuffle where Harry regains his wand with help from his friends and corners Sirius. Crookshanks guards Sirius by perching on his chest. Before Harry can act further, Professor Lupin enters, disarms Harry, and directs a question to Sirius, who points at Ron. Lupin and Sirius nod at each other and embrace, causing Hermione to scream accusations that Lupin is a traitor and a werewolf, which she had deduced from his Boggart and lunar sickness. Lupin praises her intelligence and attempts to explain himself, but is repeatedly interrupted by the trio. Finally, he hands back their wands and explains that he was using the Marauder's Map and noticed Peter Pettigrew's name with Ron's, leading him to conclude that Peter was alive and masquerading as Scabbers.
Ron struggles to accept that his pet rat is actually the Animagus form of Peter Pettigrew. Black is livid and wants to kill Peter, but Lupin insists on explaining everything first. Lupin reveals that during his youth at Hogwarts as a werewolf, Dumbledore had planned a way for him to exit Hogwarts and stay in the Shrieking Shack during full moons. This explains the Shack's name; it was never haunted, just occupied by a noisy werewolf. Lupin's friends, James Potter, Sirius Black, and Peter Pettigrew, discovered his secret. To accompany Lupin without danger, they became Animagi. The foursome explored all of Hogwarts and Hogsmeade, which helped them make the Marauder's Map. Hermione questions how this could be, noting only seven registered Animagi in the past century. Lupin confesses they were unregistered. He also admits his regret for not telling Dumbledore that Black could be an Animagus, entering the castle undetected. Lupin felt indebted to Dumbledore for his education and job, and didn't want to disappoint him. Lupin further explains that Snape, who now creates the Wolfsbane potion keeping Lupin sane during transformations, was always suspicious of Lupin's monthly disappearances. Once, Black tricked Snape into following Lupin into the Whomping Willow. James Potter had to rescue Snape from meeting the werewolf Lupin. Snape's grudge against Lupin, Black, James and his son Harry stems from this prank. As Lupin concludes, Snape appears, dropping Harry's invisibility cloak.
Snape, smirking, reveals he found Harry's dropped invisibility cloak near the Whomping Willow. He immobilizes Lupin and threatens to kill Sirius Black, dismissive of their stories due to his thirst for revenge. Eventually, the trio, Harry, Ron and Hermione, disarm him simultaneously, knocking him unconscious. Sirius explains his recognition of Scabbers, Ron's pet rat, as Peter Pettigrew from a newspaper photo gifted by Cornelius Fudge. Sirius discloses that Pettigrew must have severed his own finger, causing the rat's missing toe, before causing an explosion and disappearing. Sirius adds that Hermione's cat, Crookshanks, was his ally in chasing Pettigrew. Despite Sirius' explanations, Harry remains scared and doubtful. To remove any confusion, Lupin changes Scabbers back into Pettigrew, a balding man. Spineless Pettigrew pleads for mercy from everyone present, claiming his innocence. It is only after many revelations that Harry accepts Sirius' innocence and Pettigrew's allegiance to Voldemort, leading to the betrayal of his parents. After much hesitation, Pettigrew confesses to being Voldemort's servant. Lupin and Sirius are about to kill Pettigrew, but Harry halts them, standing up for his father's principles. Pettigrew is then tied up, placed between Lupin and Ron, and alongside an unconscious Snape, they all head back to Hogwarts.
Returning from the subterranean passageways, Black enlightens Harry about being his godfather and suggests Harry could stay with him once he's exonerated. Harry is excited by this prospect, envisioning a life away from the Dursleys. As they reach the forest, the moon becomes visible, transforming Lupin into a werewolf. With Lupin distracted, Black, in his canine form, keeps him at bay. Amid the chaos, Peter seizes Lupin's wand, stuns Ron and turns into a rat, making his escape. Following this, Black chases after Peter into the forest. Finding Ron unconscious, Harry and Hermione confirm he's still alive. Their attention is drawn to Black's human form, surrounded by numerous Dementors. Despite their efforts, Harry's patroni can't fend off the Dementors. As they weaken, a Dementor prepares to inflict the dreadful kiss on Harry. At the brink of despair, a shining figure appears, driving the Dementors away. Harry sees a large glowing creature retreat across the lake towards a man who bears a striking resemblance to his father. Overwhelmed, Harry succumbs to exhaustion and loses consciousness.
Harry regains consciousness at the hospital ward, overhearing Snape's grandiose tales of rescuing students from a werewolf and Sirius Black, with Fudge alluding to a bravery award. Despite Ron being still knocked out, Harry and Hermione energetically assert Black's innocence, citing Pettigrew's sudden appearance. Snape dismisses their accounts, attributing it to Black's mind manipulations. The debate carries on until Dumbledore steps in, requesting a private conversation with Harry and Hermione. After everyone else exits, Dumbledore reveals his belief in Black's tale, despite the lack of substantial proof. He cryptically hints at the need for more time to spare two lives, which Hermione seems to grasp. Upon Dumbledore's exit, Hermione reverses time using an hourglass pendant, transporting Harry and herself into the Forbidden Forest, just as their past selves and Ron are visiting Hagrid. Hermione quietly reveals her ownership of this time-manipulator, which allows her to attend multiple classes simultaneously, emphasizing the critical need for their future selves to avoid detection. Harry deduces the second life Dumbledore referred to is Buckbeak's. Quietly, they untie the hippogriff while the executioners are busy inside Hagrid's cabin. They then hide in the forest, hearing the frustrated axe thud and Hagrid's exultant yell at Buckbeak's unexpected escape. As Hermione and Buckbeak take shelter in Hagrid's vacant cabin, Harry sneaks out to identify the patronus conjurer. Observing the Dementors closing in for a kiss, yet no patronus appears, Harry realizes he was the original conjurer, not his father as he initially believed. He successfully conjures the stag-shaped patronus, a mirror image of his father's animagi form, saving himself, Hermione, and Black. The stag vanishes after he and Harry share a moment. Harry returns to Hermione, and together they ride Buckbeak to the tower where Black is kept, liberating both Black and Buckbeak.
Harry and Hermione return to the hospital mere moments before Dumbledore departs, matching the time they had rewound. They reveal their adventure to Dumbledore, who responds with delight. On the other hand, Snape is furious when he learns of Black's escape. He storms into the hospital, blaming Harry for Black's freedom until he's ushered out by other staff. It comes to light that Fudge has withdrawn Snape's impending award and dismissed all Dementors from the school. A sense of tranquility prevails the following day until Hagrid reports to Harry, Ron, and Hermione about Buckbeak's escape and Lupin's resignation from Hogwarts. Harry seeks out Lupin, who calmly shares his decision to keep a distance from students during his transformations. Dumbledore encounters Harry post his visit to Lupin and enlightens him about his Patronus resembling his father's Animagus form. He also commends Harry for freeing Pettigrew, which leaves Harry somewhat perplexed and melancholic as he heads back to London. On the train, Hermione reveals her intention of taking a regular course load next term while Ron suggests Harry spend the summer with him. Suddenly, a juvenile owl collides with Harry's window, delivering a note from Sirius Black. The note confirms his safety, his act of sending the Firebolt, and a request for Ron to adopt the owl in place of his lost rat. Sirius also includes a permission slip allowing Harry to visit Hogsmeade next year. Harry heads home to the Dursleys, hopeful about a better summer ahead.