Harrypotter was spending his firstyear end vaccation with his aunt Petunia,uncle Vernon and cousin Dudley
Dursley at No.4 private drive.He was not happy because he missed his school( Hogwarts school of witchcraft and wizardry ),his friends-RonaldWeasley and HermioneGranger.Above all he hated his uncle,aunt and cousin as much as they hate him.One day he recieved a warning against going back to school for his secondyear(for which he was anticipating)from a houseelf named Dobby.Harry ignored it but the elf tried the best for preventing him to go to school and even after he reached school elf tried to send him back by injuring him at QUIDDITCH ( game played on broomsticks).The reason was clear to Harry-Odd terrible things where happening at hogwarts. Harry often heard a bodyless voice talking about its desire to kill.The chamber of secrets has been opened again.According to the legend,one of the founder of the school-Salazar Slytherin who disagrred on other founders about admission of muggle born wizards( mudbloods was the term used) to school had built a secret chamber and put a monster inside it to drain the school of mudbloods.Fifty years ago the chamber has opened and one girl died.Now several students were found in petrified state.A cat and ghost was also found petrified and to cap it all the heir of slytherin left threatening messages on a wall at the entrance of abathroom which was out of order for years due to moaning myrtle-the ghost of a girl.Harry and friends suspected Draco Malfoy a slytherin student who was happiest about the current incidents.
But Harry got a diary from Myrtle's bathroom.It was a mysterious object which when written in writes back in writer's own ink.It was Tom Riddle'sdiary and he studied at school about fifty years ago and took Harry to show him what happened when chamber of secrets opened before.It showed the Hagrid was blamed for it and was expelled from school.(He was allaowed to stay by AlbusDumbledore as gamekeeper since then).It was Riddle who caught him and the monster was a baby of a giant spider who is rumoured to be in forbiddenforest.Now things were getting more tough as the governors of school decides to sack Dumbledore from Headmastership and ministry decides to take Hagrid to wizard'sprison.At the same time Harry and friends were trying to find the mystery behind this and hermione who seemed to get a clue ran to library to confirm it.But she was found petrified.But she had a paper in her hand which had all the answers.
The monster which lived inside the chamber of secrets was a Basilisk-a giant snake,most poisonous and its stare can kill people.Harry understood that noone is dead thus time because they didn't look directly to the snake's eye and the entrance to the chamber of secrets was in Myrtle's bathroom.The voice he heard was the Basilisk's and he understood because he was a parselmouth-that means he can speak snake'slanguage.But GinnyWeasley(Ron's sister) was taken into the chamber by the heir of slytherin.Harry and Ron went to chamber to rescue Ginny and Harry found Tom Riddle there.He was actually LORD VOLDEMORT and he used to possess Ginny to let the monster out and on innocent people.He grown stronger feeding Ginny's soul and was almost alive and solid while ginny was going to be dead.He unleash the Basilisk on Harry who fights the snake with the aid of GRIFFINDOR'S sword which brought to him in time by fawkes the phoenix(Dumbledore's pet).He destroyed the diary using Basilisk's fang after killing the snake and Riddle was gone.Ginny was saved.Antidote for the petrified people was successfully prepared by Hogwart's teachers and they were normal again.Dumbledore returned as headmaster and Hagrid released from jail.Lucius Malfoy(Draco's father) visited Dumbledore with Dobby who was his elf(house elfs were supposed to serve one family until they were being presented with clothes by master which was symbol of their freedom).It was lucius who planted the diary to Ginny's schoolbag.Harry tricked him into freeing Dobby as he was very cruel to Dobby.Thus everything was solved once again by Harrypotter and everyone was happy at the year end because exams were cancelled as a schooltreat.