Sherlock Holmes is drawn into a deadly vendetta that begins with a tale of ghosts and dynamite on a Scottish whisky estate, only to discover it is intertwined with his own past. Fresh from a previous case, Holmes finds himself the target of an unknown assailant. A client presents a case involving a remote Scottish whisky estate, but his brother Mycroft assigns him to a mission in the South of France. These seemingly disparate cases converge, leading Holmes and Watson to the snowy highlands where they must confront treachery, explosions, and a ghost from Holmes's own past to solve a single, deadly conundrum.

The narrative weaves together multiple plot threads, starting with a personal threat to Holmes and expanding to include a remote Scottish estate and a mission in France. The story escalates with elements of danger, including dynamite and explosions, and introduces a rival detective, Jean Vidocq. The mystery deepens as Holmes realizes the cases are interconnected, leading to a confrontation with a personal ghost from his past, challenging his rationalist beliefs. The setting shifts from London to the French Riviera and finally to the snowy Scottish highlands, providing a rich backdrop for the unfolding enigma.