Like any good Sherlock Holmes story, The Hound of the Baskervilles is riddled with clues. Being one of Doyle's longer novels, he was able to incorporate a wealth of clues both directly tied to the case and misleading for the titular hero and the reader to navigate.
1. The portrait of the Baskerville ancestor is one which immediately catches Holmes's discerning eye. He realizes by examining it that Stapleton bears a remarkable resemblance to the ancestor. This leads him to realize that Stapleton is a potential heir to the Baskerville fortune and that he is also concealing his identity, throwing suspicion away from himself.
2. The hound's attack of the convict is also telling. The convict was wearing Sir Charles's clothing, which lead Holmes to realize that the hound was trained to go after the scent of Sir Charles.
3. The theft of the boots reveals to Holmes that the beast is in fact a real flesh and blood dog, not a specter.
4. The legend of the curse is an obvious misnomer. As Holmes...
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