In the story, the brilliant consulting detective Sherlock Holmes is approached for help by his brother Mycroft, an important adviser to the British government. Ten pages of the Bruce-Partington plans, design plans for the construction of a submarine, have been stolen. Seven of those pages are discovered in the pockets of a dead man whose body is found on London Underground train tracks. The dead man is identified as Arthur Cadogan West, a government employee who worked in the building where the Bruce-Partington plans were kept but who did not have access to the safe where they were stored. Sherlock Holmes is tasked with locating the three pages that are still missing, finding out how and why Cadogan West came to be in possession of the plans, how he died and how his body came to be found o