Dr. James Mortimer asks Holmes to investigate the death of his friend, Sir Charles Baskerville. Sir Charles died at his Devonshire estate, Baskerville Hall, and Mortimer now fears for Sir Charles's nephew and sole heir, Sir Henry Baskerville. The death was attributed to a heart attack, but Mortimer is suspicious, because Sir Charles died with an expression of horror on his face, and Mortimer noticed 'the footprints of a gigantic hound' nearby. The Baskerville family has supposedly been under a curse since the era of the English Civil War, when Hugo Baskerville offered his soul to the devil for help in abducting a woman and was reportedly killed by a giant spectral hound. Sir Charles believed in the curse and was apparently running away from something when he died…