“Go back!” she said. “Go straight back to London, instantly.”

Miss Stapleton speaks to Watson when they first meet on the moor. Their encounter serves as one of the first clues Watson notes that something isn’t right on the moor or with the Stapletons. Miss Stapleton quickly takes back her words once she realizes she’s mistaken Watson for Sir Henry Baskerville, whom she wants to protect from her husband.

“Quite happy,” said she, but there was no ring of conviction in her words.

Here, Miss Stapleton’s reply that she feels happy living on the moor with her “brother,” Mr. Stapleton, doesn’t ring true to Watson’s astute ears. Watson begins to suspect that something is amiss between Miss Stapleton and Mr. Stapleton the more he observes their dynamic. Miss Stapleton’s arrival in the plot and her enigmatic responses stand as Watson’s first major break in the case.

No, no, I did not mean my husband. Sir Henry? Is he safe?

When Miss Stapleton is found bound and gagged inside Merripit House, her first words focus on Henry, not her husband, Mr. Stapleton. Miss Stapleton’s concern for Sir Henry Baskerville’s welfare demonstrates her potential feelings but also her regret for her husband’s murderous actions on the moor. Miss Stapleton has finally found a degree of relief.

It is my mind and soul that he has tortured and defiled . . . I could endure it all . . . as long as I could still cling to the hope that I had his love, but now I know that in this also I have been his dupe and his tool.

Miss Stapleton’s confession after being freed serves as a plot device to tie together the loose ends of the case of the hound for Sherlock and Watson and reveals her feelings and motivations as an unwilling accomplice in the Baskerville murders. Her admission also calls into question whether she really had any feelings for Sir Henry Baskerville.

“He may find his way in, but never out,” she cried.

Miss Stapleton, overcome with emotion, cries to Watson and Sherlock that her husband will never find his way across the mire now that a thick fog has settled in. Miss Stapleton’s claim is supported by a foreshadowing earlier in the novel as Mr. Stapleton and Watson watch a horse get sucked into the treacherous marshlands and sink to its death.