The next morning, Watson and Sir Henry discuss the advantages of the Baskerville mansion, but Watson nonetheless mentions the crying he heard the previous evening. Sir Henry admits that he also heard the sobbing, but that he thought it was just a dream. Asking Barrymore about the incident, Watson notices that the butler gets flustered. He later learns that the man's suggestion that it could not have been his wife crying is a lie—Watson sees the woman's red and swollen eyes. Watson wonders at the butler's lie and at the woman's tears, speculating that perhaps Barrymore was the bearded stranger back in London. He decides to make sure Holmes' telegraph was actually delivered into the butler's own hands, so he takes a long walk out to the Grimpen postmaster. Questioning the postmaster's delivery boy, Watson learns that the telegram was actually delivered to Mrs. Barrymore, who claimed that her husband was busy upstairs. The boy did not see Barrymore himself. Confused by the back and forth of the investigation, Watson wishes Holmes was free to come to Devonshire.

Just then, a small stranger carrying a butterfly net comes up, calling Watson by his name. Mr. Stapleton of Merripit House introduces himself and excuses his casual country manners. Mortimer had pointed Watson out, and Stapleton only meant to accompany the doctor on his walk home. Stapleton asks after Sir Henry, and expresses his concern that the baronet should continue his uncle's good works. He also remarks at the silliness of the local superstition, at the same time suggesting that there must have been something to scare the weak-hearted uncle to death. Watson is surprised that Stapleton knew of Charles' condition, but the naturalist explains that Mortimer clued him in. The doctor is equally off-put by Stapleton's subsequent mention of Sherlock Holmes, but he quickly realizes that his friend's celebrity status has preceded him, and tells the inquisitive Stapleton that Holmes is occupied in London. Watson refuses to tell Stapleton anything specific about the case, and the naturalist lauds his discretion.

Walking alongside the moor, Stapleton points out the mystery and danger of the place, highlighting the great Grimpen mire, a stretch where a sort of quicksand can suck up either man or beast. Just then, the two spot a pony being swallowed up by the sand, even though, as Stapleton brags, the pony knows his way around well enough not to get into trouble. As Stapleton dissuades Watson from trying his luck, the two hear a low, sad moan that the locals suspect is the howling of the hound of the Baskervilles. Stapleton also points out some low, stone buildings along the moor: the residences of Neolithic man.

Suddenly, Stapleton goes bounding off after a butterfly, and Watson finds himself face to face with Miss Stapleton, who has walked up unnoticed. A stunning, dark beauty—the exact opposite of her brother—she cuts off Watson's introduction by telling him to go back to London and insisting that Watson say nothing to her brother.

Reappearing at Watson's side, Mr. Stapleton discovers that his sister had thought Watson was Sir Henry, and proper introductions are made. The three make their way to Merripit House, and Watson remarks that the spot seems a strange and melancholy place for the pair to choose.

Stapleton suggests that they get along fine, though his sister seems unconvinced. The naturalist tells Watson of a previous career as a schoolmaster up north, but insists that he prefers the opportunity the moors provide for collecting and inspecting insects. Watson leaves and Stapleton asks that he tell Sir Henry of his intention to pay a visit. On the way home, Watson encounters Miss Stapleton, who has run to catch up with him. She tells him to forget her warning, though Watson presses her for more details. Miss Stapleton tries to play off her outburst, claiming to be concerned about the curse and eager not to contradict her brother, who wants a charitable Baskerville in residence. Watson is more confused than ever.