Holmes, excited by such a mysterious case, asks for more details. As it turns out, the paw prints indicated that the dog had not approached the body. High hedges and two locked gates bordered the Yew Alley. Mortimer suggests that the death was the result of some supernatural evil, and he describes his own interviews with locals, who had seen a spectral hound roaming the moors. The superstitious Mortimer only came to Holmes to ask what to do with Sir Henry, the sole heir, set to arrive at Waterloo Station in one hour. He mentions another heir, Sir Charles's brother Roger, but points out that he is presumed dead in South America. As for Sir Henry, Mortimer is afraid should he set up shop in Devonshire, but he knows that the county is counting on continued Baskerville philanthropy.
Holmes promises to consider the matter, telling Mortimer to pick up Henry at the station and bring him to the office the next morning. The detective dismisses Mortimer and Watson and settles down to contemplate the situation, ruminating in his typical fashion over a bag of Bradley's strongest shag tobacco.
Later that night, Watson returns to find the office atmosphere thick with smoke: as Holmes suggests, "a concentrated atmosphere helps a concentration of thought." Holmes surprises Watson by guessing he has been at his club and unveils a map of the Baskerville moorlands. Holmes indicates his inclination to go through all the other possibilities before falling back on the supernatural one, and he speculates on the relevant questions. Given his infirmity and fear of the moor, Holmes wonders whom Charles was waiting for at the gate. The change in footprints, Holmes suggests, indicates running and not tiptoeing. Holmes also points out that Sir Charles was running in exactly the wrong direction—away from his house and any help he might find. The duo sets aside the case and Holmes takes up his violin.
The next morning, Mortimer and the young Henry Baskerville arrive at 221b Baker Street. Though sturdy and weather-beaten, Sir Henry's expression showed that he was a gentleman. Just twenty-four hours in London, Sir Henry has already gotten involved in the mystery—he received an anonymous note of warning when he arrived at his hotel. Said the note: "As you value your life, or your reason, keep away from the moor." A few facts stand out: the address is on a plain envelope and printed in rough writing, and the note itself is composed with words cut out of a newspaper, except for the word moor. Holmes establishes that no one could have known where to reach Sir Henry, so the writer must be following him. Holmes quickly assesses the typeface and discerns that the words were cut out from yesterday's Times. He goes on to suggest that the culprit used a pair of short-bladed nail scissors, since the longer words are cut with two snips, and that the word moor was handwritten because the author could not find it in print.
Astounded, the others listen on intently. Holmes proceeds: the author must be an educated man, since only the well-educated read the Times. As such, the roughly written address suggests the writer was trying to disguise his or her handwriting, thus, the writer must have cursive that is recognizable. In addition, the author must have been in a hurry, since the words are glued carelessly onto the paper.
Dr. Mortimer, suddenly skeptical, questions Holmes' guess work, and the Holmes retorts that his methodology involves weighing probabilities and deciding on the likeliest solution. To prove it, he points out that the spluttered writing suggests a lack of ink, undoubtedly the result of a hotel pen, and not a private one. Holmes even asserts that an investigation of hotel garbage around Charing Cross, where the letter was postmarked, should yield the torn-up copy of the Times.