When a very upset Filch arrives, he accuses Harry of murdering Mrs. Norris. Harry and his friends, Filch, and the professors go to Lockhart's office and Dumbledore examines Mrs. Norris, determining that she's been Petrified, which only someone very advanced could do. Filch still accuses Harry, saying that Harry knows he is a "squib" (which Harry later finds out is a person born into a wizarding family who doesn't have magic powers). The students are cross examined by Snape, and Filch wants them to be punished, even though it is revealed that the cat can be revived. Dumbledore lets the students go. During the next few days, Hermione tries to remember what she's heard about the legend of the Chamber of Secrets. In class, she asks Prof. Binns and gets him to tell the story of how, according to legend, Salazar Slytherin (who the house is named for) built a hidden chamber in the school that was sealed until an heir would unseal it and unleash a horror on the school that would cleanse the school of all those unworthy to study magic. The students begin their own detective work, and discover that the message about the chamber is near a women's bathroom that is inhabited by the ghost Moaning Myrtle. They also begin to suspect that Malfoy is the heir of Slytherin, as he comes from a family that believes in pure wizarding blood. The students come up with a plan to get some Polyjuice Potion that will disguise them as other people, so they can find out about Malfoy.