In Sherlock Holmes’s “The Adventure of the Bruce-Partington Plans,” what is the name of the missing submarine design?

In Sherlock Holmes’s “The Adventure of the Bruce-Partington Plans,” the missing design is for the Bruce-Partington submarine.

The story was published in 1908 as part of The Return of Sherlock Holmes. Seven pages of highly secret plans for the submarine have disappeared, and a young government clerk, Arthur Cadogan West, is found dead beside railway tracks. The case combines espionage, government secrecy, and a locked-room-like question about how the documents left official custody.

Mycroft Holmes brings the case to Sherlock, emphasizing its national importance. The Bruce-Partington plans are fictional, but the story reflects early twentieth-century anxiety about naval technology and international espionage.

The title can cause confusion because “plans” refers to technical drawings rather than a military operation. The story is also notable for featuring Mycroft prominently, while Sherlock’s investigation connects the railway timetable, the corpse, and the missing documents.