Sherlock Holmes [Robert Stephens] is drawn into a pair of peculiar, unequal adventures that unfold with wit, danger, and a dash of Cold War–tinged intrigue, all while the ever-curious Dr. John Watson [Colin Blakely] documents the oddities of their world.
In the first, August 1887 brings an unusual proposition. Nikolai Rogozhin [Clive Revill], working on behalf of the famous Russian ballerina Madame Petrova [Tamara Toumanova], seeks Holmes’s help with a startling request: Petrova wishes to have a child by the legendary detective, hoping the offspring will inherit both beauty and intellect. Holmes deftly sidesteps the moral trap by claiming that Dr. Watson is his lover, much to Watson’s mortified protest. At Baker Street, Watson confronts Holmes about the rumors, and Holmes coolly replies that Watson is being presumptuous by asking about Holmes’s relationships with women. > being presumptuous
The film then shifts to a much grander, more fantastical case. Gabrielle Valladon [Geneviève Page] is fished from the River Thames and brought to 221B, where she begs Holmes to find her missing engineer husband. The investigation widens in startling directions, eventually steering them toward the banks of Loch Ness. On the way, the duo encounters a curious menagerie: a group of monks and a crowd of dwarfs, and Watson himself seems to glimpse the legendary Loch Ness monster. They observe canaries and a cache of sulfuric acid being carried into a castle undergoing renovation, and deduce the canaries are used to detect chlorine gas produced when the acid meets sea water.
As clues accumulate, it becomes clear that Holmes’s own brother, Mycroft Holmes [Christopher Lee], is entangled in the affair. Mycroft is overseeing a Royal Navy project to build a submersible, aided by M. Valladon’s air pump, a critical component for the vessel’s success. When tested, the craft is disguised as the Loch Ness Monster, an audacious ruse that doubles as a weapon. The crew is infiltrated by dwarfs precisely because their size helps them operate within the submarine’s confines, a detail that starkly illustrates the film’s quirky logic.
The deception unravels when Mycroft reveals the client is not a benign petitioner but a top German spy, Ilse von Hoffmanstal, sent to seize the air-pump. The “monks” guiding the ship are German sailors, and Queen Victoria [Mollie Maureen] herself arrives to inspect and ceremonially launch the vessel—yet she is troubled by its unsportsmanlike nature. She orders Mycroft to destroy it, but the vessel is left unguarded long enough for the monks to seize it, and the plan is set in motion. Fräulein von Hoffmanstal is arrested, to be exchanged for a British spy held elsewhere, bringing the espionage plot to a high-stakes pause.
Months later, Sherlock receives word that von Hoffmanstal has been captured as a spy in Japan and executed by firing squad. The revelation devastates Holmes, who retreats to his room and seeks solace in a 7% solution of cocaine, a stark counterpoint to the clever, calculating mind that propelled both cases.
The two tales weave together a tapestry of espionage, fantasy, and deduction, anchored by the iconic partnership of Holmes and Watson. They trade wry banter and shrewd observations, navigate danger that veers from the practical to the mythic, and ultimately reveal how a master detective contends with betrayal, secrecy, and the darkest intrigues of a world on the cusp of modern warfare.
