After finding out that he is a famous wizard, Harry returns to the Dursleys for the summer. Dobby, a house-elf, warns him not to go back to Hogwarts. Harry refuses to promise not to return, and so Dobby performs a Hover Charm for which Harry is punished. The Dursleys lock Harry in his room. The Weasleys come to rescue Harry using a flying car. They bring Harry to their house where he stays for the rest of the summer. He and the Weasleys visit Diagon Alley to pick the things they need for school. While inside a bookstore, they have a nasty encounter with Lucius.
When term begins, Harry and Ron are left behind by the train. They take the flying car but crashes into the Whomping Willow. While in detention for this stunt, Harry hears voices which Lockhart did not. During Halloween, Harry hears the voices again and follows it to a warning written in blood on the wall that the chamber of secrets had been opened. Hanging underneath was the petrified cat of Filch.
Hermione asks Professor Binns about the legend of the chamber of secrets. He tells them that because of the disagreement between the four founders of Hogwarts, that is, Slytherin wished to limit magical pureblood families, a serious argument ensued and Slytherin left Hogwarts, but not before building a chamber where only his heir can open. Rumors spread that Harry was the heir of Slytherin.
During a Quidditch game against the Slytherins, Harry is injured by rogue bludger. While in the hospital wing, Dobby tells him that the chamber of secret was opened before. Dobby disappeared just as Dumbledore and Professor McGonagall brings in a petrified Colin Creevey into the hospital wing.
A dueling club is started by Lockhart. During a demonstration, Harry and the rest of the school finds out that he is a parseltongue, that is, he can talk snake language. Another attack happens, this time it was Justin and Nick who were petrified. Harry is sent to Dumbledore’s office. While inside the office, he asks the sorting hat if he was sorted correctly. The hat stands by what he said, that Harry could do great things in Slytherin.
Harry finds a blank diary which belongs to a T.M. Riddle thrown away in the girl’s bathroom. He finds its magical secret and goes back to the night that Riddle allegedly caught the heir. Harry is surprised to find out that it was Hagrid and the monster was a giant spider. The diary is stolen from Harry’s trunk.
Hermione and another girl are attacked. Harry and Ron use the invisibility cloak to ask Hagrid about the monster. But before Hagrid could respond, the Minister comes to arrest Hagrid. Lucius Malfoy also comes to tell Dumbledore that he has been replaced as headmaster. Dumbledore leaves Hogwarts but tells Harry that help will always be given by those who ask for it. Hagrid also tells them to follow the spiders if they want to find out what happened. They follow the spiders into the Forbidden Forest and finds out that it was not the giant spider which was the monster. Harry realizes that it was Moaning Myrtle who was the victim of the monster. They also find a paper in Hermione’s hand which says that the monster is a basilisk which kills by its stare. Before they could tell anyone, Ginny is taken to the Chamber of Secrets.
Harry and Ron go to Lockhart to tell him what they know because they thought that as DADA teacher, he would rescue Ginny. Instead they find him packing to leave. They bring him with them to the Moaning Myrtle’s bathroom, where, using parseltongue, Harry suceeds in opening the chamber of secrets. Harry, Ron, and a reluctant Lockhart go down but, Lockhart grabs Ron’s wand and attempts to perform a memory charm on them. The wand mafunctions because it was damaged by the whomping willow and backfires on Lockhart. However, Ron and Lockhart are cut off by the rocks that fall down and so Harry continues to search for Ginny. He finds her in the heart of the chamber with Riddle. Harry finds out that Riddle is Voldemort. Voldemort attempts to kill him using the monster but Harry prevails. He uses the fangs of the basilisk to kill the diary. Ginny wakes up and confesses that she was possessed by Riddle and was the one who wrote the warnings on the wall.
In Dumbledore’s office, Harry tells the tale. Ginny is sent to the hospital wing, Ron and Harry get special awards and two hundred points each for Gryffindor. Dumbledore assures Harry that despite what Riddle said about their strange likeness, he is different because of the choices that he had made. Lucius Malfoy bursts in with Dobby to find out whether Dumbledore was indeed back. Dobby hints to Harry that Malfoy was the one who put the diary in Ginny’s cauldron. Harry confronts him but Malfoy leaves. Harry runs after Malfoy and hands him the diary with his sock hidden in between, who in turn hands it to Dobby who discovers the sock. He tells Malfoy that he is free because his master handed him a piece of clothing.
Gryffindor wins the House cup and Hagrid returns. The year comes to an end, and its time again to return to the Dursleys for summer.
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