Down a dark hall chapter 4 summary?

Chapter 4 of "Down a Dark Hall" by Lois Duncan starts with Kit making another discovery about Blackwood - there are secret passageways throughout the grounds, and these lead to various sections of the school, including the forbidden Black Hall.

One night, at the urging of her new friend Lucy, Kit decides to explore the Black Hall. She sneaks out of her dorm room and makes her way through the passageways, eventually arriving at the Hall.

Inside, she finds a library filled with strange books, old medical equipment, and bizarre objects in glass cases. This Hall seems to be the place where the school conducts its more disturbing experiments.

As she's exploring, she encounters Madame Duret, who appears upset that she's there and tells her to return to her dorm.