ONE mystery was soon cleared up: a strange figure on a distant tor proved to be Holmes himself, pursuing his own investigation. He had discovered something much less supernatural than the Baskerville legend, but just as dangerous.

A near neighbour of Sir Henry’s, Jack Stapleton, was really a Baskerville himself, who would inherit if Sir Henry died. But motive alone was not enough. Stapleton must be caught in the act.

So Holmes encouraged Stapleton to invite Sir Henry for dinner. The baronet would have to walk alone across the moor by night, an opportunity Stapleton could not refuse.

Trusting to local superstition and the Baskerville legend, Stapleton let loose a huge and ravenous dog, its teeth smeared with phosphorous, its scent trained on Sir Henry’s missing boot.

But Holmes was lying in wait. He shot the slavering hound even as it sprang, and Stapleton, in trying to escape across the moor, was lost without trace in the treacherous Grimpen mire.