At school, Harry begins to hear voices in the walls. Mysterious writing appears on the walls saying "the Chamber of Secrets has been opened". The Chamber of Secrets is a mysterious part of the school built by Salazar Slytherin, one of the four founders of Hogwarts. The school staff learn that Ron's younger sister, Ginny, has been taken into the Chamber. Harry finds a magic black diary written by a former student named Tom Riddle.