It was released on 15 November 2002 in the United Kingdom and North America. The film was very well received at the box office, making US$879 million worldwide and is the 30th highest-grossing film of all time. and the seventh highest-grossing film in the Harry Potter series. It was nominated for three BAFTA Film Awards in 2003.
Preparing for a visit from a potential client of Uncle Vernon Dursley's, the Dursleys send Harry to his room. Harry finds Dobby the house elf, who warns him against returning to Hogwarts. When Harry refuses, Dobby causes havoc in the house, thereby ruining Vernon's meeting. Vernon locks Harry in his room to prevent his return to Hogwarts. That night, Ron, Fred, and George Weasley arrive in their flying car to rescue Harry from the clutches of Uncle Vernon, who discovers the rescue and tries to pull Harry back into his room. The Weasleys succeed and take Harry to The Burrow, their home. Harry meets Ron's younger sister, Ginny, who is about to begin at Hogwarts and has a crush on Harry. Harry also meets Ron's father, Arthur Weasley; he had met Mrs. Weasley the previous year. Harry and the Weasleys travel to Diagon Alley by Floo Powder. While shopping, Harry meets Gilderoy Lockhart, a famous wizard and author, and later Draco Malfoy and his father, Lucius, who praise Voldemort and deride Harry, Hermione and the Weasleys.
At King's Cross Station, though the rest of the Weasleys reach Platform 9 3/4 without trouble, Harry and Ron find the magical barrier blocked; as a result, they miss the Hogwarts Express. Harry and Ron take the flying car and reach Hogwarts, but accidentally land in the school's violent tree, the Whomping Willow. Ron's wand is broken and the car behaves erratically, ejecting the boys and driving itself into the Forbidden Forest. When Harry and Ron enter Hogwarts they are seen by Snape, who scolds them for flying the car to Hogwarts and nearly expels them. Professor McGonagall and Professor Dumbledore arrive and McGonagall defends the boys and tells them they will receive detention only.
Shortly after the start of term, Harry begins hearing an ominous, icy, cold voice coming from inside the walls, starting in his detention with Lockhart. Harry, Ron and Hermione find the message "The Chamber of Secrets has been opened. Enemies of the heir, beware" written in blood across a wall and discover that caretaker Argus Filch's cat has been petrified, who blames it on Harry and attempts to attack him but is stopped by Dumbledore and McGonagall. Legend has it that the Chamber of Secrets can only be opened by the Heir of Slytherin; it is said to be the home of a creature that will only obey the Heir. Harry suspects the Heir is Malfoy. Gilderoy Lockhart, hired to teach Defence Against the Dark Arts, offers a dueling club. At the meeting Draco conjures a snake that Harry discovers he can talk to. Hermione explains that he is a Parselmouth like Salazar Slytherin, a connection that causes the school to believe Harry is his Heir. The three brew Polyjuice Potion to disguise themselves as Malfoy's friends Crabbe and Goyle, and interrogate Malfoy, but learn that he is not the Heir.
In a bathroom Harry finds a book with nothing written in it that belonged to someone named Tom Marvolo Riddle. Through the enchanted book Harry sees events that happened fifty years ago when Tom was a student. Tom's memories incriminate Hagrid as the Heir.
Over the course of the school year, Colin Creevey, Justin Finch-Fletchley, the Gryffindor ghost Sir Nicholas and even Hermione are all found petrified, and Tom Riddle's diary goes missing. Harry and Ron decide to ask Hagrid, but before Hagrid can answer the real identity of who opened the Chamber, Minister of Magic Cornelius Fudge and Lucius Malfoy arrive. While Ron and Harry hide, the visitors tell Hagrid they are suspending Dumbledore as headmaster and arresting Hagrid under suspicion of having opened the Chamber. Before Hagrid is taken away to Azkaban prison, he tells Ron and Harry to follow the spiders into the Forbidden Forest for the truth. They do so and meet Aragog, a giant spider thought to have killed a student fifty years ago. Aragog reveals that he is not the monster who killed the student and that Hagrid is innocent. Aragog's sons and daughters attack Harry and Ron, but the flying car rescues them and they escape the forest.
Harry and Ron learn from a piece of paper in Hermione's hand that the monster is a basilisk, a giant snake that can kill anyone just by looking at them in plain sight and overhear the teachers saying that Ginny has been taken into the Chamber. Lockhart is sent to find the Chamber and save Ginny, but tries to escape until Harry and Ron catch him. It turns out Lockhart's past is false; he used memory-erasing charms on witches and wizards to take credit for their accomplishments. The three find the chamber entrance in Moaning Myrtle's (the girl who died the first time the Chamber opened) bathroom and enter to find a giant snake skin. After he faints, Lockhart tries to stop Harry and Ron by using a memory charm, but because he used Ron's broken wand, it backfires. Lockhart loses his memory and part of the Chamber caves in, separating Harry from the others and forcing him to rescue Ginny alone. Harry finds Ginny unconscious, and slowly dying, and Tom Riddle appears, explaining that he is a memory preserved in the diary. Riddle tells Harry that Ginny Weasley opened the Chamber, sent the basilisk to attack and wrote threatening messages on the walls because he ordered her to. Harry learns that Riddle is Slytherin's Heir and is Lord Voldemort in his teenage form. Riddle sends the basilisk to kill Harry but Dumbledore's phoenix, Fawkes, attacks the basilisk's eyes blinding it. Fawkes gives Harry the Sorting Hat, from which he draws the sword of Godric Gryffindor. Although Harry kills the basilisk by driving the blade up through its head, a fang embeds itself in his arm and poisons him.
Harry destroys Voldemort/Riddle by piercing the diary with the fang. Ginny regains consciousness and finds Harry dying, but Fawkes heals Harry's wound with his tears. Dumbledore resumes his post as Headmaster and sends in the paperwork to have Hagrid released from Azkaban. Dumbledore assuages Harry's concerns of his worthiness to belong to Gryffindor House by pointing out that only a true member could have summoned Godric's sword. Learning that Lucius gave the diary to Ginny and that Dobby serves the Malfoys, Harry tricks Lucius into freeing him from servitude. At the year-end feast, Hermione along with all of the basilisk's victims are back to full health, and Hagrid receives a standing ovation as he returns to Hogwarts.
In a post-credits scene, a new Gilderoy Lockhart book is on display at Flourish & Blotts, entitled "WHO AM I?" and depicting an amnesiac, confused Lockhart in a straitjacket.