Sir Charles Baskerville has suffered an unusual death, causing some to say he was yet another victim of the dreaded family curse, which warns of a fabled hellhound haunting the Scottish moors. Not one prone to superstition, Sherlock Holmes (Jeremy Brett) thinks something else is afoot. Being stuck in London himself, Holmes sends his colleague, Dr. Watson (Edward Hardwicke), to investigate instead. It soon becomes clear to them both that Baskerville's demise was no mere accident.