Because of the petrification of Mrs. Norris, many students still did not realize the severity of the situation. They all began to wonder what the so-called Chamber of Secrets actually was and where it might be. Harry and his friends also tried to look for clues, but had no idea where to start.
In the end, it was Hermione who thought of a clue: if the so-called Chamber of Secrets truly existed, Professor Binns, who taught History of Magic, would certainly know. They decided to seize the opportunity to ask this only ghost professor at Hogwarts during their history class.
"Hmph, that rigid old man knows, does he?"
Chapter 54