The Hound Of The Baskervilles is the eponymous secondary antagonist of the Sherlock Holmes story of the same name.
According to an old account, said to have been written in 1742 and describing events which had occurred a century earlier still, during the English Civil War, Hugo Baskerville was infatuated with a farmer's daughter. He kidnapped her and imprisoned her in his bedroom. She escaped and the furious Baskerville offered his soul to the devil if he could recapture her. Aided by friends, he pursued the girl onto the desolate moor. Baskerville and his victim were found dead. She had died from fright, but a giant spectral hound stood guard over Baskerville's body. The hound tore out Baskerville's throat, then vanished into the night.
In the present day, Mr. Jack Stapleton thought he could use the wicked legend to his advantage.