In the eerie wasteland of Dartmoor, Sherlock Holmes summons his devoted wife and partner, Mary Russell, from her studies at Oxford to aid the investigation of a death and some disturbing phenomena of a decidedly supernatural origin. Through the mists of the moor there have been sightings of a spectral coach made of bones carrying a woman long-ago accused of murdering her husband - and of a hound with a single glowing eye.

Returning to the scene of one of his most celebrated cases, The Hound of the Baskervilles, Holmes and Russell investigate a mystery darker and more unforgiving than the moors themselves.