The Adventure of the Bruce-Partington Plans

This story takes place in November 1895. Sherlock Holmes and Watson are visited by Mycroft, Sherlock's brother, and Lestrade, in order to investigate the strange death of a scientist on the London Underground, who had seven original plans of the secret submarine Bruce-Partington, inexplicably stolen from a Navy safe, where he worked. In addition to this, three papers are missing, which are the most important to build this submarine. The matter has caused great concern in the highest offices of the British government, and they expect a quick and effective response from Sherlock Holmes, who fears that these plans may already be on the European continent.