(This drabble was born after reading Neil Gaiman's 'A Study in Emerald' – I couldn't help wondering what 'The Hound of the Baskervilles' would have been like if the Baskerville legend had actually been true... Note: Bruja is Spanish for 'sorceress'.)
...Fire burst from its open mouth, its eyes glowed with a smouldering glare, its muzzle and hackles and dewlap were outlined in flickering flame...
Watson looked up from the latest Strand with a shiver. "Honestly, Holmes... I still have my doubts as to your phosphorous theory."
Holmes arched a sardonic eyebrow. "You have a sound alternative?"
"Well, not as such, but... Holmes, you know as well as I that the real case had far too many loose ends! Why didn't the Hound savage Sir Henry as it did the others? Sir Charles, Selden... Mrs. Stapleton..." Watson shuddered at the memory. "Moreover, if it was an ordinary dog, why didn't any of our shots seem to hit it? And don't tell me the fog threw off all of our aims again!"
Holmes frowned obstinately, but Watson wasn't having any of it.
"Holmes," he sighed, "we've both learned firsthand over the years that anything is possible. Why are you so averse to the idea that we might have encountered the supernatural on this case?"
Holmes's hands tightened on the arms of his chair. "Because the only theory that fits all the facts, Watson," he whispered, "I find too dreadful even to contemplate..."
That only Sir Henry's good heart had saved him from the ambitions of Beryl Garcia, Stapleton's devoted wife, and practising bruja...