The book begins with Harry returning home to the Dursleys for the summer.
As usual, they make his stay miserable by locking him in his room with no one to talk to except his owl, Hedwig. Harry wishes to go back to Hogwarts but the Dursleys won’t allow it. One day, Dobby, a house elf, appears warning him that terrible things will happen if he decides to return. Harry refuses to believe the elf and continues to pack to leave. In the middle of the night, his friends Ron, Fred, and George appear with a flying car stealing Harry away for the rest of the summer.
As Harry and the Weasleys go shopping for Hogwarts at Diagon Alley, they encounter the Malfoys and also Gilderoy Lockhart, Hogwarts’ new Defense Against the Dark Arts teacher. They then try to abroad the train at Platform Nine and Three-Quarter to go to Hogwarts however Harry and Ron are unable to. As a result, Ron steals his family’s flying car and tries following the Hogwarts train back. They land roughly in which they are caught and given detention and Ms. Weasley finds out and scolds
Ron.
Days later Quidditch practices start. Draco Malfoy is made the new seeker for team Slytherin. He insults Hermione, calling her a “Mudblood”, because she is a Muggle. This angers Ron in which he tries to curse Draco, however it ends up causing him to vomit slugs. He is rushed to Hagrid and after they leave, Professor McGonagall gives Harry and Ron detention. During Harry’s first detention, he hears a strange voice in the corridors. He also hears this same voice during the Halloween feast. Harry follows the voice into a bathroom where sees the caretaker’s, Argus Filch’s, cat hanging next to a wall where “The Chamber has been opened. Enemies of the heir beware.” is written. Dumbledore, the headmaster, concludes that dark magic that no student could perform was used.
Harry, Ron, and Hermione are shocked and wish to find out more about this dark magic. They research find out from Professor Binns that the Chamber of Secrets, created by Salazar Slytherin, was opened 50 years ago and killed a student. They also find out that only the Heir of Slytherin can control the monster inside the chamber.