Hearing a slight noise in the West wing, she had peeped along the passage, and had seen Mr. John Cavendish knocking at Mrs. Inglethorp's door. 
She was stalking Mr. John Cavendish that night.
mnli hypothesis: She was stalking Mr. John Cavendish that night. premise: Hearing a slight noise in the West wing, she had peeped along the passage, and had seen Mr. John Cavendish knocking at Mrs. Inglethorp's door. 