Chapter Summaries

Harry intercepted Astoria’s secret admirer letter and wrote a reply for her, while Hermione began an intense study of Arithmancy. A week later, Goyle and Crabbe left school, and Professor Lupin prepared to teach his first practical Defense Against the Dark Arts lesson.

• Harry took Astoria’s pink letter, read the admirer’s confession, and wrote a reply for Astoria to deliver without opening.
• Hermione brought Harry to the library and declared she would master Arithmancy within half a year and surpass Professor Trelawney.
• Goyle and Crabbe withdrew from school after rumors spread that their fathers had been fired by the Ministry of Magic.
• Snape focused his criticism on Neville during Potions class after Harry ignored his jibes and Hermione answered his questions correctly.
• Lupin led the students to the staff room for a practical Defense Against the Dark Arts lesson, and Snape warned him about Neville, Harry, and Hermione before leaving.

Professor Lupin taught the third-year students how to defeat a Boggart, and Neville and the others practiced the Riddikulus spell. When the Boggart faced Harry, it became another Harry before he transformed it into a smiling expression and destroyed it; Hermione left wondering what she feared most and what Lupin’s crystal ball meant.

• Professor Lupin explained how Boggarts sensed people’s fears and taught the class to use Riddikulus.
• Neville faced a Boggart shaped like Professor Snape and made it wear his grandmother’s clothes, while Parvati and the other students also defeated frightening forms.
• The Boggart became a silver-white sphere in front of Professor Lupin, who turned it into a leaking balloon.
• The Boggart took Harry’s form, and Harry transformed it into a smiling expression that made it vanish.
• Hermione wondered what she feared most and asked Harry about the crystal ball that had appeared before Professor Lupin.

Harry and Hermione grew disgusted with Trelawney’s predictions, while Lupin and Hagrid’s classes continued to engage the students. As Quidditch season approached, Harry watched Cho Chang train and refused Wood’s request to reveal Ravenclaw’s tactics, prompting rumors about him in Gryffindor.

• Lupin taught students about Red Caps and Kappas, while Malfoy attended classes quietly and Snape continued to punish Neville in Potions.
• Hermione told Harry that Trelawney had insulted them and made ominous predictions, and she resolved to expose Trelawney as a fraud.
• Hagrid introduced his class to creatures including Bowtruckles, Thunderbirds, Demiguises, and Occamies, and Malfoy performed well.
• As Quidditch training began, Harry accompanied Cho Chang to Ravenclaw practice and learned that the team planned to build its strategy around her Firebolt.
• Wood asked Harry to share Ravenclaw’s training plans, but Harry refused, and rumors that he was cold and heartless spread among Gryffindor students.

Hermione told Harry how Wood had slandered him, and Harry pretended to threaten Wood with a deadly curse before Hermione stopped him. As Ravenclaw trained under Harry’s magical shelter, Helena posted notice that eligible students could visit Hogsmeade at Halloween, while Ron said Scabbers would soon return.

• Hermione recounted Wood’s version of their dispute, and Harry amused her by pretending to cast a spell that could kill him.
• Harry created a magical dome to keep Cho Chang and the Ravenclaw Quidditch team warm and dry during training.
• Helena continued as Hogwarts administrator, and Harry left dangerous-looking pills on the notice board as a joke for students hoping to court her.
• Helena posted a notice allowing third-year students and above to visit Hogsmeade on Halloween weekend with a signed application.
• Harry handed Hermione his Astronomy star-chart homework to draw, and Ron said Scabbers was nearly well and would arrive before Halloween.

On the full moon, Snape brought Lupin a goblet of Wolfsbane Potion, then substituted for him in Defense Against the Dark Arts and condemned his teaching. The students were left to begin a lesson from the back of their textbooks as Snape claimed they should learn to fight dragons by graduation.

• Harry watched Lupin’s office from the Hogwarts rooftop as Snape delivered the Wolfsbane Potion and warned Lupin to drink it.
• Lupin drank the potion and considered telling Snape that Sirius Black had been framed, but Snape’s hatred made him hold back.
• Snape entered Lupin’s Defense Against the Dark Arts class as a substitute and criticized Lupin’s teaching.
• Hermione defended Lupin, but Snape argued that students needed tougher training and should be able to fight dragons by their seventh year.
• Snape told the students to turn to the back of their textbooks, and they hurried to find the assigned pages.

Snape’s substitute Defense Against the Dark Arts lesson consisted of making the class copy a chapter on Werewolves and assigning a lengthy essay, while Hermione researched the subject and stumbled onto a startling idea about Dumbledore. The chapter ended with Hermione preparing to explain her discovery to Harry.

• Harry correctly identified page 394, and Hermione’s comparison of Werewolves to Huskies led a wizard to misunderstand Muggles’ relationship with the animals.
• Snape criticized Lupin’s teaching, made the students copy the Werewolf chapter, and assigned four rolls of parchment on Werewolves.
• When Ron challenged his authority, Snape threatened to fail him in Potions if his assignment was unsatisfactory.
• Hermione and Harry went to the library, where Hermione researched Werewolves for the essay.
• Hermione made a discovery involving Dumbledore, fetched a booklet to check it, and told Harry she had a bold idea.

Hermione deduced that Professor Lupin was a werewolf but chose not to expose him, believing he was a qualified teacher. Later, Scabbers arrived at Hogwarts and fled in terror after seeing a large black dog beneath Harry’s bed.

• Hermione explained how Lupin’s changing appearance, absences around the full moon, and the Wolfsbane Potion led her to suspect he was a werewolf.
• Harry told Hermione that exposing Lupin to the Daily Prophet could force him out of Hogwarts, and Hermione decided to pretend she knew nothing.
• On October 23, Ron received Scabbers, his family’s elderly rat, and said the rat had been ill and needed strengthening pills.
• Scabbers sensed Sirius Black’s Animagus scent but convinced himself he was safe at Hogwarts.
• After Ron brought Scabbers into the Gryffindor dormitory, the rat saw a huge black dog beneath Harry’s bed and bolted down the stairs as the dog chased him.

Sirius Black chased Scabbers through Hogwarts but lost him, while Peter Pettigrew planned his escape. Harry Potter caught Peter and killed him, ending his flight.

• Scabbers escaped Sirius Black in the common room, and Black lost track of him in the entrance hall.
• Peter hid in a wall crevice, realized Black had found him, and planned to flee Hogwarts and report him to the Ministry of Magic.
• Peter recalled betraying James and his friends for Voldemort, then spending more than ten years disguised as a rat.
• Peter left the crevice believing he had escaped, but Harry Potter stepped on him and pinned him to the floor.
• Harry told Peter it was over, severed his limbs with magic, and carried away his body.

Snape, Lupin, and Black converged on the Shrieking Shack after Harry summoned them, and their past conflict reignited when Snape attacked Lupin. Harry arrived with a mutilated man and said the others could settle their own business.

• A black-clad Snape entered the passage beneath the Whomping Willow, and Lupin and Black followed him to the Shrieking Shack.
• Snape and Lupin confronted each other, and Lupin tried to explain that he had known nothing about Black's prank years earlier.
• Black arrived and embraced Lupin, prompting Snape to bind Lupin and threaten to send them both to Azkaban.
• Black wondered where Harry was and realized Harry had summoned him and Lupin to the Shack.
• Harry appeared with a mutilated man and told the others that he did not need to be involved in their business.

The chapter recounted how James, Black, Peter, and Lupin became Animagi and secretly visited Lupin during his transformations. When Snape followed Lupin to uncover his secret, James saved him from the transformed Werewolf, but Snape left furious and the two sides became enemies.

• James, Black, and Peter learned Animagus transformation so they could accompany Lupin when he transformed into a Werewolf.
• The four friends explored Hogwarts and Hogsmeade at night and created the Marauder's Map under their nicknames.
• Snape followed Lupin to the Whomping Willow, and Black revealed how to enter the passage as a prank.
• Snape encountered the transformed Lupin, but James pulled him back into the passage and shut the trapdoor.
• Snape threatened to reveal that Lupin was a Werewolf, yet he kept the secret and became enemies with James's group.

Harry revealed that Peter Wormtail, presumed dead, was the Potters’ actual Secret-Keeper, casting doubt on Snape’s belief that Black betrayed Lily and James. Black explained that he had persuaded the Potters to choose Peter and blamed himself for their deaths, while Snape remained hostile and the truth still awaited confirmation from Peter.

• Snape accused Black of betraying Lily and causing her death, but Black and Lupin recognized the badly injured man as Peter Wormtail.
• Harry told Snape that Wormtail had been the Potters’ Secret-Keeper, making Snape hesitate and agree to hear what Wormtail had to say.
• Snape bound Black and Lupin with thorny vines, then loosened Black’s restraints enough for him to speak.
• Black explained that he had persuaded Lily and James to make Peter their Secret-Keeper because everyone expected Black to hold the role.
• Black said he found Peter’s hiding place empty, discovered the Potters’ home in ruins, and blamed himself because his plan had led to their deaths.

Harry forced Peter to explain himself while Snape questioned Black and struggled to trust him. Peter claimed Black had killed Lily and James, but Black exposed him as the traitor who had revealed Lily’s location, and Peter tried to defend himself by claiming he had secretly protected Harry.

• Snape grabbed Black by the collar and accused him of fooling Harry, while Harry tried to get them to focus on the truth.
• Harry scraped Peter’s hair away to reveal his identity, then beat him until Peter stopped pretending to be unconscious.
• Peter crawled to Snape and claimed Black and James had bullied him and forced him to do their bidding.
• Peter said he had hidden from Black because Black had killed Lily and James, but Snape challenged his story about anticipating Black’s escape from Azkaban.
• Black accused Peter of betraying Lily to Voldemort and hiding from the Death Eaters, while Peter denied it and claimed he had secretly protected Harry.

Harry stopped Snape from killing Peter before Black’s name was cleared, and Peter confessed to betraying Lily and James under the Cruciatus Curse. After Black apologized to Snape for the past, Snape led the group away to treat Black’s injuries.

• Snape nearly killed Peter, but Harry invoked his mother to interrupt the spell and save Peter until Black’s name could be cleared.
• Snape tortured Peter with the Cruciatus Curse, and Peter confessed to betraying Lily and James.
• Harry cast a soundproofing spell while Peter screamed, and Snape released Black and Lupin from their bonds.
• Harry urged Black to apologize to Snape for the incident that had nearly gotten Snape killed at school, and Black apologized.
• Snape told Black to come with him for treatment, and Lupin floated Peter as the group left the house.

Harry brought Lupin, Sirius Black, Snape, and Wormtail out of the Shrieking Shack and to Dumbledore’s office, where Black explained what had happened. Dumbledore agreed to take the case to the Ministry of Magic and have the Wizarding Court reopen it.

• Lupin began transforming under the moonlight, but Snape poured Wolfsbane Potion into his mouth and helped him change back safely.
• Harry and the others brought Wormtail and the weakened Lupin to Dumbledore’s office, where Dumbledore recognized Wormtail and inferred that Black’s case had been misjudged.
• Black recounted his story to Dumbledore and admitted that he had entered Hogwarts as an unregistered Animagus.
• Dumbledore said the revelations would cause a major uproar and told Black to prepare to go with him to the Ministry of Magic the next day.

Dumbledore brought Sirius Black and Peter Pettigrew to the Ministry of Magic, revealing that Pettigrew had betrayed James and his wife to Voldemort. At Hogwarts, Hermione questioned Professor Trelawney’s divination after Parvati claimed Trelawney had predicted Lavender’s pet rabbit would die.

• Dumbledore told the Ministry operator he had captured Sirius Black and Peter Pettigrew, the true traitor who had exposed James and his wife to Voldemort.
• Peter Pettigrew realized he was finished as the elevator carried him and Dumbledore underground to the Ministry.
• Harry and Hermione skipped Divination to study Arithmancy in the library, where Hermione said she had always earned full marks in Muggle mathematics.
• Parvati taunted Hermione for abandoning Trelawney’s class and claimed Trelawney had predicted something Lavender feared would happen on October 16.
• Parvati explained that Lavender had received a letter saying a fox had bitten her pet rabbit to death, leaving Hermione stunned by the prediction.

Hermione argued with her classmates over Trelawney’s prediction and condemned the professor as a fraud. After Transfiguration, McGonagall told Harry that he had been permitted to visit Hogsmeade.

• Hermione challenged Lavender’s claim that Trelawney had predicted her rabbit Binns’s death, but her classmates rejected her reasoning.
• Ron accused Harry’s dog of chasing Scabbers away, and Dean repeated Trelawney’s insults and warnings about Harry and Hermione.
• Hermione denounced Trelawney as a fraud, and Harry praised her argument as the other students left.
• McGonagall told the class that third-years needed signed permission slips to visit Hogsmeade, then said Neville had lost his form.
• McGonagall stopped Harry after class and told him he had been permitted to visit Hogsmeade.

Professor McGonagall gave Harry a Hogsmeade permission form signed by Sirius Black and said Sirius would explain why he might become Harry’s guardian. At lunch, Harry agreed to help Astoria sneak into Hogsmeade, then protested when Hermione accused him of allowing Astoria to kiss him.

• Professor McGonagall told Harry that Sirius Black had signed his permission form and would explain his connection to Harry’s family.
• Harry explained that a boy who bragged about Hogsmeade was trying to impress Astoria, then teased her with a ridiculous dating tip.
• Astoria told Harry she wanted to visit Hogsmeade, and he agreed to think of a way to take her despite the rules.
• Astoria kissed Harry on the cheek, and Hermione rebuked him for letting the twelve-year-old kiss him.
• Harry claimed he had been assaulted and asked why Hermione was not defending him.

Harry moved into a lavish apartment created by the Room of Requirement and spent a snowy Sunday reading while Little Cutie kept him from turning her into a cat-eared girl. The chapter ended with Harry lamenting that life rarely went as he wished.

• Harry joked indignantly to Hermione about the unfair treatment of male wizards, and Astoria corrected his description of the weather.
• After moving out of the Gryffindor dormitory, Harry used the Room of Requirement to create a luxurious apartment and invited Hermione and Cho Chang to stay with him; Hermione threw a book at him, and Cho Chang beat him in a staring contest.
• Harry studied a manga beside the fireplace while Little Cutie curled up against his hand.
• Harry asked Little Cutie to transform into a cat-eared girl, but she covered the book and urged him to stop reading such stories.

Harry debated Lupin about whether Dark magic was inherently evil, then learned from the Daily Prophet that Peter had confessed and Sirius Black’s case would face a major international trial. Harry later spent time with Hermione, Astoria, and Cho Chang in the snow.

• Harry told Lupin that magic itself was morally neutral and that a wizard’s intentions mattered more than the spells they used.
• Lupin showed Harry a Daily Prophet report stating that Peter had confessed to betraying Lily and James and that Sirius Black was awaiting trial.
• Lupin explained that Sirius’s trial was scheduled for January and that Fudge and Barty were trying to influence the hearing.
• Harry joined Hermione and Astoria, and the three went to find Cho Chang.
• Harry watched the four of them play in the snow and reflected that he had few friends despite having a large harem.

Harry helped Hagrid prepare pumpkins and vegetables for Hogwarts’s Halloween feast, then spoke with Helena in the library. Helena left hurt after Harry questioned whether they were close, despite her believing their shared history made them friends.

• Harry helped Hagrid harvest pumpkins and prepare jack-o'-lanterns for Halloween.
• Hagrid told Harry that foxes had continued killing his chickens despite using fox repellent.
• Harry suggested Hagrid raise only hens or magically prevent the chickens from crowing, hinting that a dangerous creature might fear their sound.
• Helena approached Harry in the library and asked why he had not spoken to her.
• Helena remembered how Harry had returned Ravenclaw's Diadem to her and how she had come to trust him.
• Harry asked Helena whether they were really that close, and she apologized before turning away in tears.