House of Fear — Willo Davis Roberts

Never has Brooke been so frightened. She and her younger brother arrive at Miss Tansy's to spend the summer. But Elsa, the housekeeper, refuses to let them see the old woman.

During the next few days Brooke's fears grow. Miss Tansy is locked in a room upstairs. And strangely enough, the handsome boy Elsa hires as cook knows his way around the house.

Brooke begins investigating, and when she uncovers the truth, finds herself prisoner in the house of fear.