What are the clues given throughout the novel?

• The portrait of the Baskerville ancestor reveals a remarkable resemblance to Stapleton.

• The hound attacked the convict, who was wearing Sir Charles's clothing. The clue.... the hound was trained to follow and attack Sir Charles' scent.

• When the boots are stolen, Holmes realizes that the "hound" is dog. It is not a specter.

• Holmes doesn't believe in curses.... there has to be a rational explanation.