Sherlock Holmes (Peter Cushing) and Doctor Watson (Andre Morell) meet with a certain Dr. Mortimer (Francis De Wolff), who tells them of the legend of the "hound," born out of a murder committed by Sir Hugo Baskerville centuries ago. Explaining that Sir Charles Baskerville recently died in the same location as Sir Hugo, Mortimer expresses his deep concern that Sir Henry, the heir to the Baskerville estate, will also fall prey to the evil hound's curse. Holmes sets out to investigate.