Harry Potter and the Chamber of Secrets

Harry is having a terrible summer. He has been waiting for his friends to send him letters all summer. One day he gets a visit from a house elf named Dobby. Dobby warns him that something horrible is going to happen at Hogwarts this year. Harry decides to ignore this warning and attend school for his second year. Could the elf have been right?

The Worst Birthday

On July 31 (Harry's Birthday), Aunt Petunia, Dudley, and Uncle Vernon were having a dinner party for one of Vernon's clients, Mr. Mason, and Harry had to stay in his room for the night "pretending he doesn't exist". However, when he gets there, something else is on his bed...

Dobby's Warning

The thing on his bed, a house elf named Dobby, tells Harry that he mustn't go back to Hogwarts because it would be dangerous and bad things are happening however refuses to tell him what bad things. In the process, he makes too much noise, and Harry receives a warning from Uncle Vernon. Dobby then reveals that he had stopped letters being sent to Harry, and offers them in return for Harry not returning to Hogwarts; however Harry refuses and Dobby run down stairs and uses a Hover Charm to smash the dinner party's pudding. An owl from the Ministry of Magic is promptly received (scaring Mrs. Mason away) with a warning saying that Harry has violated Decree for the Reasonable Restriction of Underage Sorcery and giving him a warning. After realizing that Harry isn't allowed to do magic outside school after all, Uncle Vernon locks Harry in his room. Vernon reasons that if Harry uses magic to get himself out, he will be expelled anyway.

The Burrow

This win-win situation for the Dursleys lasts for three days until Ron, and Fred and George Weasley, worried about not hearing from Harry all summer, borrow their father's enchanted Ford Anglia, which is capable of flight, and come to the rescue. On the flight to the Burrow Harry explains Dobby's warning. They all agree that most likely Dobby belongs to a rich person who sent Dobby to Harry as a joke (mostly believed to be Draco Malfoy). When Harry is taken to the Burrow, the Weasleys' home, he finds the house truly amazing. Since Ron, Fred and George snuck the car out they get caught and yelled at by Molly. After they yelling she makes them breakfast and has the three Weasley boys De-Gnome the garden, and Harry volunteers to help too. When Arthur comes home he is introduced to Harry who is honored to meet him and his wife yells at him for enchanting the car. Ginny, who is enrolling at Hogwarts this year and has a very obvious crush on Harry spends most of the chapter hiding from Harry.

At Flourish and Blotts

Harry stays at the Burrow until his departure for Hogwarts. During that period, he and the Weasleys travel to Diagon Alley with Floo powder in order to get their school supplies. Harry has difficulty with the smoke around him and says "Diagon Alley" unclearly (in the film he says "diagonally"), and thus he accidentally lands in a shop in the ill-reputed Knockturn Alley instead. The shop is Borgin and Burkes, specialising in objects related to the Dark Arts. There he sees Lucius Malfoy, father of none other than Draco Malfoy, Harry's arch rival from school, selling items related to Dark Magic to a dark arts salesman, Mr. Borgin. Malfoy explains that the Ministry has been conducting raids on wizard houses in order to uncover illegal artefacts, so he is selling his more problematic possessions. He also expresses his disdain for a rumored Muggle Protection Act, which he (rightly) assumes Arthur Weasley is behind.
Harry leaves the shop to be found by Hagrid and taken back to Diagon Alley to reunite with the Weasleys and Hermione Granger, who is also there with her parents. In Flourish and Blotts, he and the Weasleys meet the famous wizard/author Gilderoy Lockhart, who announces that he will be taking over as Hogwarts' new Defence Against the Dark Arts teacher. He then forces Harry to have his picture taken with him for the main page of the Daily Prophet. They also meet Draco and Lucius Malfoy there. The elder Malfoy continuously taunts and insults Arthur and his family and eventually Arthur lunges at him. During the fight, Malfoy grabs one of the Weasleys' second-hand books and subsequently throws it back at Ginny in contempt.

The Whomping Willow

On the way to the Hogwarts Express, when Harry and Ron try to go through the barrier to platform nine and three quarters, the barrier mysteriously is sealed against them. Having missed the train, Harry and Ron thus decide to fly Mr. Weasley's flying Ford Anglia to Hogwarts. They end up getting spotted by many Muggles and crash into the Whomping Willow. Professor Severus Snape attempts to have them expelled, but fails to convince the headmaster, Professor Albus Dumbledore. Still, both boys are given a warning and separate detentions. Ginny, meanwhile, is sorted into Gryffindor.

Gilderoy Lockhart

The next day, Ron receives a Howler from his mother and both Harry and Ron have their first lesson with Gilderoy Lockhart, appointed as the new Defence Against the Dark Arts's teacher. His way of teachings is a complete disaster. Much to Harry's chagrin, he receives constant attention from Lockhart and Colin Creevey, a first year student. Both constantly interact with him on the base of his fame (Colin treats Harry as a celebrity and Lockhart hopes to actually bring him to that state). Harry also faces unwelcome attention from Ginny, albeit in a less intrusive manner.

Mudbloods And Murmurs

The Gryffindor Quidditch team has a very early practice on Saturday morning, where they are treated to an hour-long introduction to a new training program Oliver Wood spent the summer working on. Soon after the actual practice starts, the Slytherin Quidditch team, with new Nimbus 2001 broomsticks, arrives, and an argument over field time insues. During the confrontation, Malfoy is revealed to be the new Slytherin seeker, and the one responsible for getting the Slytherin team new brooms. Malfoy calls Hermione Granger a Mudblood, and Ron tries to curse him. However, his damaged wand causes it to backfire and he is rushed to Hagrid's cabin when he starts vomiting slugs. For his detention, Harry is made to help Lockhart answer his fan mail, while Ron polishes the school's prizes and trophies. During his unpleasant punishment, Harry hears a disembodied, sinister voice which Lockhart is unable to hear.

Deathday Party

In return for distracting Argus Filch just when he's about to give Harry severe punishment, Harry promises he'll come to Nearly Headless Nick's Deathday Party on Halloween. He brings Ron and Hermione along as well, but the three of them quickly get tired of the ghostly party and return to the Great Hall. Before they get to the Halloween feast, Harry hears the voice (which Ron and Hermione also cannot hear) and follows it to the second floor, where he finds the bathroom flooded and Mrs. Norris, Filch's cat, petrified—coupled with a message on the wall, reading
THE CHAMBER OF SECRETS HAS BEEN OPENED.
ENEMIES OF THE HEIR, BEWARE.

The Writing on the Wall

Filch and Snape try to get Harry in trouble for this, but Dumbledore says that it is powerful dark magic that no second year student could perform. They decide that Professor Sprout's mandrakes will be used, once they are mature enough, to create a draught capable of reviving Mrs. Norris. Hermione wants to research the Chamber, so she persuades Professor Binns (the History of Magic teacher) into telling the class about it. He explains that one of the founders of Hogwarts, Salazar Slytherin, got into an argument with the others about whether Muggle-borns should be admitted. When the rift grew too large, he left the school. According to legend, he built a going-away present to the school in the form of a secret chamber that could only be opened by his true heir. This "Chamber of Secrets" contains a monster that only the Heir of Slytherin can control that, once released, would purge the school of all Muggle-borns. Binns unsuccessfully tries to assure the class that the Chamber does not actually exist and that the school has been searched many times in vain.

Rogue Bludger

Harry, Ron and Hermione decide that the heir is probably Draco Malfoy. To try to prove it, Hermione proposes to use Polyjuice Potion, which can change a person into somebody else for an hour. After getting Lockhart's signature to check out the book Moste Potente Potions from the Restricted Section that has the recipe, Hermione warns them that the potion will take a month to brew, supposing they gather all the necessary ingredients (one of which can only be found in Snape's private inventory) and manage to keep it a secret. Since no one comes into Moaning Myrtles' bathroom, the three of them decide it is the best place to brew the potion unnoticed. During the month that it takes the Polyjuice Potion to brew, a Quidditch match between Gryffindor and Slytherin takes place. During the match, one of the Bludger stakes after Harry and focuses completely on him. Since Bludgers are supposed to attack each and every player, the crowd immediately realizes that this Bludger has been tampered with. Harry still manages to catch the Golden Snitch and Gryffindor wins. However, the Bludger breaks Harry's arm, and Lockhart, attempting to fix it, gets rid of all the bones in his arm instead. Madam Pomfrey gives Harry Skele-Gro potion to counter this and Harry is forced to stay in the Hospital wing overnight. During that night, Dobby visits Harry and reveals that it was he who made the Bludger chase after Harry, and was also responsible for the barrier of platform nine and three-quarters not letting him in for in hopes of Harry leaving or never arriving at Hogwarts. He also reveals that the Chamber of Secrets has been opened before and immediately punishes himself, as he is not supposed to reveal anything. After Dobby disappears, Dumbledore, McGonagall, and Madam Pomfrey enter with Colin Creevey, who has apparently been petrified. He was found with a camera containing film that has been burnt to the melting point.

Duelling Club

Harry signs up for a Duelling Club which, to Harry's great displeasure, is taught by his two least favourite teachers, Lockhart and Snape. During a practice battle in the first meeting, Draco Malfoy conjures a snake to attack Harry. Lockhart tries to banish it, but all he manages is to set it loose on the students. Harry sees that the snake is advancing on a Hufflepuff student named Justin Finch-Fletchley and instinctively tells it to stop, which-to Harry's great surprise-it does. He expects Justin to be grateful; on the other hand, he and the others are less than ecstatic about it. All they saw was Harry speaking Parseltongue, the language of snakes, and since they cannot understand it, it seemed to them that he was egging the snake on. Harry learns that Parseltongue is a very rare gift that is closely associated with Salazar Slytherin. Due to this, Harry becomes the number one suspect among students for being the heir of Slytherin. Hermione even tells him that since Salazar Slytherin lived so long ago, he might actually be a descendant.
When a Herbology lesson is cancelled, Harry has a talk with Hagrid, who reveals that the school's roosters are being mysteriously killed. Seconds after leaving Hagrid, Harry runs into a petrified Justin Finch-Fletchley and a black, smoking Nearly-Headless Nick. Peeves alerts the whole school, and a Hufflepuff called Ernie Macmillan claims that Harry has been caught red-handed.

Polyjuice Potion

For the first time, Harry is taken to Dumbledore's office, and there he witnesses Fawkes—Dumbledore's phoenix—bursting into ashes and being reborn. Dumbledore says that he doesn't believe Harry to be behind the attacks, a belief reinforced by Hagrid backing Harry's alibi, but a large portion of the school is now sure that Harry is Slytherin's heir. Harry, Ron and Hermione all sign up to remain in the School during Christmas, since Malfoy, Crabbe, and Goyle have done so as well, and this gives them the perfect opportunity to use their Polyjuice potion. When Christmas arrives (Harry's gifts: a toothpick, fudge in a tin, a copy of Flying with the Cannons, a new quill, a jumper and plum cake) they drug Crabbe and Goyle via chocolate cakes, take their hairs and assume their form. Hermione tries to use a hair she thought belongs to Millicent Bulstrode, but it's actually her cat's cat hair and Hermione is transformed into a cat/human hybrid. Hermione is forced to spend a few weeks in the Hospital wing. As Crabbe and Goyle, Harry and Ron interrogate an unsuspecting Malfoy and discover that even though he wishes he were, Draco is not the Heir of Slytherin. They also hear that the last time the chamber was opened, fifty years ago, a muggle-born girl died and whoever was responsible was expelled. Malfoy also mentions his father's secret stash of illegal artifacts.

The Very Secret Diary

Weeks later, Ron and Harry overhear Argus Filch complaining about his workload and leaving. They arrive at Moaning Myrtle's bathroom to find it flooded. Myrtle, a sulking ghost, explains that she had flooded it because somebody flushed a diary down the toilet and onto her. Harry picks it up; it turns out to have belonged to one T.M. Riddle and to be completely blank. Ron remembers from his detention that Riddle had won an award for special service to the school fifty years before. Hermione deduces that since this coincides with the last time the Chamber was opened, Tom Riddle might have received his prize for catching whoever was responsible for the attacks back then. Even though all attempts to extract information from the diary fail, Harry feels a strange compulsion to keep it.
On Valentine's Day, Ron and Harry are dismayed to find out Lockhart has spread dwarves dressed as cupids throughout the school to receive and deliver Valentines. One cupid-dwarf manages to deliver one to Harry. While struggling to avoid him, the embarrassed Harry trips and falls, having ink spilled all over the contents of his bag. Ginny notices the diary and assumes a horrified expression. Later, Harry realizes that even though ink was spilled all over the diary, it is not stained at all. He tries writing to the diary and, to his surprise, T.M. Riddle-writes back. Riddle explains that he was the one who caught the person who opened the Chamber of Secrets the last time, and he can show Harry what happened. Harry agrees and gets sucked into a "recording" of Riddle's memory. He witnesses the school's previous headmaster, Armando Dippet, informing Riddle that the school will be closed and Riddle, apprehensive of this, catching Hagrid fiddling with a large spider in a box. Riddle reports Hagrid to Dippet. During the memory we also learn that Riddle was an orphan that did not want to go back to the orphanage, and his full name was Tom Marvolo Riddle. Having seen this, Harry wonders whether Hagrid was the one who opened the Chamber fifty years before and whether he is responsible this time.

Cornelius Fudge

Harry, Ron and Hermione decide not to ask Hagrid about it, hoping that the attacks have stopped-and indeed, almost four months after the attack on Justin and Nearly-Headless Nick, the disembodied voice keeps quiet and the attacks seem to have ceased. However, odd things keep happening: Harry returns to his dormitory one day to find it a mess. Ron deduces that somebody has been looking for something, and Harry eventually notices that Tom Riddle's Diary is gone. This greatly befuddles them, seeing as only a Gryffindor could know the password to enter the dormitory.
The next day, the scheduled Quidditch match between Gryffindor and Hufflepuff is cancelled due to yet another attack and Harry hears the voice again. This time Minerva McGonagall calls for Harry and Ron personally, and leads them to the Hospital wing where they see Hermione petrified. She was found near the library with a Ravenclaw prefect, inexplicably holding a small, circular mirror. This removes Harry as a suspect in the eyes of many of the students.
Harry and Ron decide they now must talk to Hagrid. With the now constant supervision on students this isn't easy, but they manage to do it by using Harry's Invisibility cloak. When they reach Hagrid's cabin Harry and Ron manage to hide just before Cornelius Fudge-the Minister for Magic-and Dumbledore arrive at the scene. Fudge announces that Hagrid, who to the best of his knowledge opened the Chamber of Secrets the last time, will be sent to Azkaban prison as a precaution. They are shortly joined by Lucius Malfoy, who declares that he and the other governors of Hogwarts have unanimously voted to suspend Dumbledore, despite the obvious logic that this would only worsen the situation. Both Hagrid and Dumbledore give last words. Hagrid says that if anybody wants the truth they should "follow the spiders" and Dumbledore says that he will only truly have left the school when none there remain loyal to him. He also stresses that if anybody at Hogwarts needs help, it will always be available.

Aragog

Harry and Ron decide to follow the spiders as per Hagrid's advice. Walking along the trails of the spiders, which are strangely all fleeing Hogwarts, takes them into the Forbidden Forest. Even though Ron is deeply arachnophobic, the fact that Hermione has been petrified and that they may be able to help through this investigation gives him the willpower to go along anyway. There, they encounter Arthur Weasley's car, which had apparently taken to driving through the forest like some sort of wild animal. They eventually meet Aragog, an aging Acromantula which had been the monster Hagrid had been "caught" setting on other students 50 years ago. Aragog explains that Hagrid is innocent, but rather than letting Harry and Ron go he decides to leave them as dinner for his children. Mr. Weasley's Ford Anglia comes blasting through the layers of spiders, however, and lets the boys escape.
After this, Harry and Ron feel that they have reached dead ends everywhere, until one possible last hope occurs to them. Aragog said the monster's last victim died in a bathroom and it occurs to Harry that Moaning Myrtle might have been that victim. Of course, with the school under such security, it will be almost impossible to sneak in the girls' bathroom near where the first attack occurred.

The Chamber of Secrets

Later that same day, Harry and Ron manage to trick Lockhart - who is leading them to their next class - into letting them go by stroking his ego. Just as they pat themselves on the back, they get caught by Professor McGonagall, and Harry has to make up an excuse - they were going to see Hermione in the Hospital wing, where visitors were now barred. They now have to go along to make their story appear convincing, but rather than simply hanging around Hermione's petrified form, this time Harry notices a piece of paper tightly clutched in her hand. This piece of paper reveals what Hermione had found out before she was attacked. She had discovered, based on strong circumstantial evidence, that the monster in the Chamber of Secrets was a basilisk. As a basilisk is a giant snake this explains why only Harry could hear it. The Basilisk kills people by looking it in the eye, but no one died, because nobody had looked at its gaze directly. Colin Creevey saw it through his camera, Justin Finch-Fletchley saw it through Nearly-Headless Nick (who was already dead), Mrs. Norris saw a reflection of it in the waters of the flooded bathroom, and Hermione used a mirror to look around corners after figuring things out. There is also a note about how spiders fear the Basilisk (which explains spiders fleeing Hogwarts) and the rooster's call being potentially fatal to it (which explains Hagrid's roosters having been mysteriously killed during the year). On the note is also scribbled a single word, "pipes", which means that the serpent moves around through the plumbing.
Having solved the mystery, Harry and Ron decide to go to the staff room and report to the teachers. When they get there, they overhear the teachers talking about another attack having occurred. Harry and Ron decide to hide to hear more details, and learn that Ginny has been kidnapped and the heir of Slytherin has left another message under the previous one:
HER SKELETON WILL LIE IN THE CHAMBER FOREVER Harry and Ron also hear that Hogwarts will be closed tomorrow. The teachers then force Lockhart to deal with the monster, as he has been claiming he could handle whatever is responsible for the attacks, irritating the rest of the staff to no end. Looking very crestfallen, he leaves for his room.
That night, Harry and Ron feel utterly useless and helpless, until it occurs to them that if the serpent uses the plumbing to get around and the last time the chamber was opened a girl died, then the chamber entrance must be in the bathroom Moaning Myrtle haunts.
Harry and Ron decide that if Lockhart is going to deal with the monster they might as well tell him what they know. They go to his room, only to find him frantically planning to run away. When questioned on why such a talented wizard as himself is leaving, Lockhart admits that he is a fraud and that he put Memory Charms on the people who really did the things that he claimed to have done in his books. He then attempts to put a memory charm on Harry and Ron as well, but they manage to disarm him and, under wand threats, take him to Moaning Myrtle's bathroom.
Moaning Myrtle explains her death, saying the last thing she saw was a pair of enormous eyes by one of the sinks, the tap of which has never worked. Harry finds a snake carved on the tap and then opens the entrance to the Chamber of Secrets by speaking Parseltongue to it.
Harry, Ron and Lockhart slide down a large pipe and find themselves in maze-like tunnels far under the school. Down there, they encounter a snake skin left by the Basilisk. Just then, Lockhart feigns fainting and he steals Ron's wand. Victoriously proclaiming that he will erase Harry and Ron's memories and tell everybody they lost their sanity at the sight of Ginny's mangled body, Lockhart fires. Ron's broken wand causes the charm to backfire, erasing Lockhart's memory and causing a portion of the ceiling to cave in. This traps Harry in the direction of the chamber and Ron in the direction of the castle. Ron has no choice but to stay behind and clear a path through the rocks while Harry continues in search of Ginny. Harry then encounters a wall with stone snakes on it, opens it by speaking Parseltongue and enters the Chamber itself.

The Heir Of Slytherin

Inside, he finds Ginny lying on the ground, pale and cold. He drops his wand and runs to her, trying to get a response from her, to no avail. He then sees Tom Riddle smiling at him and holding Harry's wand. Riddle explains his presence in the present by revealing he is a memory, which had been preserved in his diary for fifty years.
He then explains what had happened. Riddle had opened the Chamber of Secrets fifty years ago and planned to purge the school of Muggle-borns; however, when he learned that the school was going to close down due to the attacks and that Dumbledore (then the Transfiguration teacher) was keeping a closer and closer watch on him, he had no choice but to cease the attacks and frame Hagrid for doing it. Not wanting to waste all the years he spent on figuring out where the chamber was and how to get to it, he left behind a diary containing the memory of his sixteen-year-old self in hopes that it would, one day, fall into the hands of an unsuspecting victim who would help him finish his work.
Ginny had been writing in the diary all year. Riddle had written back sympathetically and Ginny grew to confess her fears, hopes and feelings to him. She essentially poured some of her soul into him, which was exactly what he wanted. He gradually grew more powerful and eventually managed to pour some of his soul back into her, possessing her and using her body to open the chamber and launch the new series of attacks. However, eventually Ginny became suspicious of the diary and decided to get rid of it by flushing it down the toilet in Moaning Myrtle's bathroom. This is when Harry found it.
When Ginny saw Harry with the diary on Valentine's Day, she panicked and worried that Riddle had told all of her secrets to Harry, so she stole it back from Harry's dormitory. It began taking control of her again, but this time with the intention of killing Harry, so he had Ginny write her own farewell on the wall and come down to wait, luring Harry to the rescue and, consequently, his doom.
Riddle then asks how Harry managed to defeat the Dark Wizard Lord Voldemort as a mere baby. Harry asks Riddle why he cares, as Voldemort existed after his time. Riddle replies that Voldemort is his "past, present and future." He then writes his name in the air with Harry's wand:
TOM MARVOLO RIDDLE
Riddle then waves the wand and the letters rearrange themselves into
I AM LORD VOLDEMORT
Needless to say, this means Riddle grew up to become Lord Voldemort. Riddle then reveals he is, in fact, a half-blood, and his mother had named him Tom after his Muggle father and Marvolo after his wizard grandfather, a descendant of Salazar Slytherin. He scrambled his name to create a new one, which he knew people would fear when he became the greatest sorcerer in the world.

Basilisk

Harry retorts that he must be mistaken, because the greatest sorcerer in the world, as everybody knows, is not Voldemort but Albus Dumbledore. Even when Voldemort was at the peak of his power he was afraid of Dumbledore, and now he's barely alive. Riddle angrily answers that Dumbledore has been driven out the castle by the mere memory of him. Harry yells that Dumbledore is not as gone as Riddle seems to believe. In this display of loyalty he summons Fawkes the phoenix to him, who also brings with it the Sorting Hat, both assets that Riddle deems extremely useless.
Riddle then summons the Basilisk and commands it to kill Harry. However, Fawkes isn't as defenceless as one might initially think, and pecks out the Basilisk's eyes, thus preventing its gaze from killing. The basilisk can still smell Harry, however, and remains very dangerous, so Harry, in desperation, puts on the Sorting Hat, wishing against hope for help. Instead of an answer, Harry has a heavy sword with a hilt embedded with rubies fall on his head from inside the hat. After several missed strikes from the blinded Basilisk, Harry plunges the sword into the roof of its mouth, killing it. However, one of its poisonous fangs sinks into his arm, injecting a deadly poison. While Riddle gloats over his "win", Fawkes cries on the wound, and since Phoenix tears have incredible healing properties, Harry is instantly cured.

Basilisk's fang

Harry then plunges the Basilisk fang into the diary. Ink begins pouring out of the book and the memory of Riddle fades out of existence; Ginny immediately stirs and wakes up, quite distraught. Harry and Ginny travel back through the Chamber to find Ron and Lockhart, who has no idea of who or where he is.
Harry, Ron, Ginny and Lockhart grab onto Fawkes and fly out of the Chamber (another Phoenix speciality). They return to the castle to find Dumbledore, McGonagall, Arthur and Molly Weasley, who are delighted to see them alive. Harry worries that Ginny will get blamed for being the person behind the attacks, but to his great relief Dumbledore rightly deduces that Voldemort is the culprit. After Ginny leaves to get a much-needed rest, Harry and Ron both receive two hundred house points each for Gryffindor and both get an Award for special services to the school, and then Dumbledore asks to speak with Harry alone.
Harry expresses his concern that he belonged in Slytherin. Dumbledore reveals that Voldemort transferred some of his powers to Harry when he gave him his scar, explaining his ability to speak Parseltongue. He asks Harry why he thinks the Sorting Hat put him in Gryffindor if he has so many Slytherin qualities, and Harry admits that the only reason it did was because he had asked it to. Dumbledore confirms this and tells Harry that "it is our choices, rather than our abilities, that reveal who we truly are". He points out to the sword Harry had drawn out of the hat - Harry now notices it has Godric Gryffindor's name on it. Dumbledore says that only a true Gryffindor would be able to draw it out.

Dobby's Reward

Lucius Malfoy barges into Dumbledore's office, outraged that Dumbledore had returned to the school after being dismissed. Dumbledore calmly responds that the governors had asked him to return once they heard that Arthur Weasley's daughter was attacked. Apparently they had been blackmailed by Malfoy to vote for Dumbledore's dismissal in the first place under Malfoy's threat of cursing their families. Dobby follows Lucius into the room, thus showing that his masters are the Malfoys.
Dumbledore and Malfoy have a calm but venomous interchange (respectively), during which Dumbledore and Harry (with the help of Dobby's unspoken hints) essentially expose Lucius sneaking Riddle's diary (one of his illegal artifacts) into Ginny's school things during the fight with Arthur at Flourish and Blotts. This was supposed to frame Ginny for the attacks, with heavy implications on the Muggle Protection Act Arthur Weasley had been suggesting. Malfoy dares Dumbledore to prove his accusation, and while the Headmaster has insufficient evidence to do that, he cautions Malfoy against orchestrating further such plots.
Knowing that a master can release his house-elf by giving them some clothes, Harry tricks Malfoy into freeing Dobby by giving Malfoy one of his own socks, which he promptly throws away to be caught by Dobby. Malfoy's retribution is thwarted by the now free Dobby, who then thanks Harry profusely and disappears. The petrified people are cured, Hagrid is released from Azkaban, Lockhart is sent to a hospital and Lucius Malfoy is fired from his post as school governor. The book ends with Harry at King's Cross, crossing the barrier back to the Muggle world.