It is 1890, and in the days before Christmas, Sherlock Holmes and Dr. John Watson are visited at Baker Street by a new client. Eve Allerthorpe, eldest daughter of a grand but somewhat eccentric Yorkshire-based dynasty, is greatly distressed, as she believes she is being haunted by a demonic Christmas spirit. Her late mother told her terrifying tales of the sinister Black Thurrick, and Eve is sure that she has seen the creature from her bedroom window. What is more, she has begun to receive mysterious parcels of birch twigs, the Black Thurrick’s calling card.

Three linked crimes test Sherlock Holmes’ deductive powers, and his skepticism about the supernatural, to the limit.

The year 1894. The monstrous Hound of the Baskervilles has been dead for five years, along with its no less monstrous owner, the naturalist Jack Stapleton. Sir Henry Baskerville is living contentedly at Baskerville Hall with his new wife, Audrey, and their three-year-old son, Harry. Until, that is, Audrey’s lifeless body is found on the moors, drained of blood. It would appear some fiendish creature is once more at large on Dartmoor and has, like its predecessor, targeted the unfortunate Baskerville family.

It is the autumn of 1880, and Dr. John Watson has just returned from Afghanistan. Badly injured and desperate to forget a nightmarish expedition that left him doubting his sanity, Watson is close to destitution when he meets the extraordinary Sherlock Holmes, who is investigating a series of deaths in the Shadwell district of London. Several bodies have been found, the victims appearing to have starved to death over the course of several weeks, and yet they were reported alive and well mere days before.

Sherlock Holmes’s discovery of a mysterious musical score initiates a devious Christmas challenge set by Irene Adler, with clues that are all variations on the theme of “theft without theft”, such as a statue missing from a museum found hidden in the room it was taken from. In the snowy London lead-up to Christmas, Holmes’s preoccupation with the “Adler Variations” risks him neglecting the case of his new client, Norwegian arctic explorer Fridtjof Nansen, who has received a series of threats in the form of animal carcasses left on his doorstep.