Two visitors come to Sherlock Holmes’s London home in Baker Street to ask for the detective’s help. Holmes is interested in the story, but he sends his friend, Dr Watson, to Dartmoor to begin the investigation. Dartmoor is the dark and lonely place where Sir Charles Baskerville died – or was it murder? The clues are worrying, too. An enormous wild dog killed Sir Charles’s ancestor there a hundred and fifty years earlier. Suddenly, people hear terrible howls again on the moor!