Now ensconced at Baskerville Hall, Dr. Watson writes a daily letter to Homes reporting on facts and occurrences as they arise. He's already noted several possible lines of inquiry. Watson has met a neighbor, Mr. Stapleton and his sister, Beryl. The household staff, the butler Barrymore and his wife, have been acting strangely and Watson has actually seen the man signaling someone on the moor. He's also heard Mrs. Barrymore crying at night. As Sir Charles becomes interested in Beryl Stapleton and insists on venturing out alone, Watson does his best to protect him. There are others on the moor however, as Watson will soon learn.
—garykmcd