Musing on the mysteries of the case, Watson dismisses the supernatural explanation but admits that his common sense offers no obvious solution. Where might a living and breathing hound hide by day, and who is the mysterious shadow out on the moor? Watson determines to find out what this man might know and whether he is the same person who provided the warning back in London.
Meanwhile, Sir Henry argues with Barrymore over the chase of his brother-in-law, Selden. Watson and Henry worry that the man is a public danger. Nonetheless, Barrymore assures them that Selden is just biding his time until a ship arrives for South America, and that he will not commit any more crimes. Barrymore's betters agree not to tell the police, and Barrymore thanks them by offering another clue. Apparently, Sir Charles went to the gate on the night he died to meet a woman, and Barrymore tells of his wife's discovery of a charred letter, signed L.L., requesting the late-night meeting.
The next day, Watson learns from Mortimer that Laura Lyons, daughter of "Frankland the crank," lives nearby in Coombe Tracey. Mortimer goes on to explain that Laura married an artist against her father's will and that both husband and father have since abandoned her. In the meantime, both Stapleton and Sir Charles have come to her aid by offering her alms.
As for the silhouette on the moor, Watson learns from Barrymore that Selden has seen him, too. He appears to be a gentleman, and he lives in one of the Neolithic huts along the moor, getting his food from a young boy.
Deciding that an informal visit might be the most productive, Watson leaves Sir Henry at home and heads for Coombe Tracey. At Laura Lyon's apartment, Watson meets the beautiful brunette and announces his interest in the matter of Sir Charles' death. Suspicious but finally cooperative, Laura admits that Sir Charles supported her financially, and that she wrote to him once or twice. But when Watson presses the issue, she claims to have had very little to do with him personally, and that it was Stapleton who told him of her situation.
Watson goes on to mention the burned letter, and Laura finally admits to having written it. The lateness of the hour and the strangeness of the location, she claims, resulted from her just having heard of Charles' imminent departure and her fear that a late-night meeting might look bad. When Watson asks what happened that night, Laura claims to have missed the appointment, but she refuses to say why. All she will disclose is the letter's content: an appeal for alms from Sir Charles to get her out of a bad marriage. Laura also adds that in the interim, she has gotten help from someone else.
Frustrated, Watson takes his leave, wondering what Laura might be holding back. Meanwhile, the doctor determines to search for the mysterious stranger on the moor. Watson is particularly determined because he wants to show up his master, Holmes. On his way home, Watson bumps into Mr. Frankland and agrees to have a glass of wine with him. As Frankland prattles on about his various legal matters, Watson realizes that the man has unwittingly spotted the stranger on the moor, thinking him to be the escaped convict. The man Frankland saw had a young boy bringing him food, just as Barrymore described the stranger's setup. Watson prods Frankland for more information, and just then, the man spots someone out on the moor and goes for his telescope. Sure enough, they see a young boy who is glancing behind him as if to make sure no one is watching.
Watson declines Frankland's offer for another drink and makes his way to where he saw the boy. Finding the stranger's hut, Watson decides to wait for his return. Examining the contents of the hut, the doctor discovers a note that says he has gone to Coombe Tracey and he realizes that he is also being followed. Finally, Watson hears footsteps outside and a sudden greeting.
These chapters further explore Watson's character, and his desire to triumph over Holmes. For example, he says, "It would indeed be a triumph for me if I could run him to earth, where my master had failed," showing that he is perseverant, despite his ability to ever solve mysteries as well as Holmes. He represents the frustration we feel at not being able to solve the mystery without Holmes (or the author's) help. Watson tries to take on the mysterious stranger on the moor before Holmes finds him. The irony of the situation, of course, is that the stranger will turn out to be none other than Watson's master. Through no fault of his own, Holmes will humiliate the well-meaning Watson.
Watson stumbles on to Holmes with the help of Frankland, the story's cranky comic relief. In hindsight, the two men are an interesting and ill-informed pair. Frankland convinced he has spotted the convict and Watson is convinced he really knows what is going on. In the end, we realize that neither of them are correct, and Holmes has out-witted them again.
At the end of this section, Doyle uses a classic suspense technique: the cliffhanger. Regularly employed in virtually all genres, the cliffhanger comes from a tradition of serialization and is not exclusively a mystery story tactic. Back when fiction was often printed in segments—little bits of the story published each week or month in a periodical—the cliffhanger kept people coming back for more. The cliffhanger ensured that they would buy the next issue of the magazine, that they would read the next installment, and sometimes, that the whole of the story would later be bound and sold as a book. The Hound of the Baskervilles was serialized in the Strand magazine before it was ever published as a whole. The notion of a serialized story reminds us that many of the most famous authors simply wrote because they needed to make money. Writers like Charles Dickens would write hundreds and hundreds of pages, and keep the story going by adding a cliffhanger at the end of every chapter. Similarly, Doyle only wrote Hound because of the public appeal for more Sherlock Holmes adventures, and because Doyle was experiencing financial problems. As a result, Hound is one of the longest Sherlock Holmes adventures he ever wrote.