Despite warning of danger and obstacles by the house elf Dobby, Harry returns to Hogwarts for his second year by Weasley’s flying car after spending part of his summer with the Dursleys and the rest with the Weasleys. His excitement of being back with his friends, however, is soon overshadowed by a series of mysterious petrifications of creatures and students at Hogwarts. Harry learns that this is done by a monster locked inside the Chamber of Secrets built by one of Hogwarts’ founder Salazar Slytherin many years ago. Harry is determined to find out who opened the door to the Chamber of Secrets and let out the monster. Harry, Ron and Hermoine suspect Malfoy first, but he turns out to be innocent. Then, accidentally, Harry finds a diary book that writes back when you write on it. The diary mentions that Hagrid opened the door. Harry follows the hint but fails again. Eventually Harry manages to find access to the Chamber of Secrets by talking to Mourning Myrtle, ghost of a girl who was killed the last time the chamber was opened fifty years ago. It turns out that Voldemort has taken control of Ginny Weasley through the diary book and ordered her to open the door to the Chamber of Secrets. Harry defeats the monster and rescues Ginny out of the chamber.