His Last Bow (Sherlock Holmes #8)

Just before World War I. Before getting ready to head to Berlin a German agent is awaiting one final package that contains important naval signals. A mysterious tenant lives with a London landlady and is never seen leaving his apartment. An older wealthy woman vanishes from her house. Despite ten sheets being discovered next to the body of a navy clerk the highly secret submarine construction designs are missing. These cases—along with many others—are brought to the Baker Street residence of Sherlock Holmes. But the most well-known detective in the world and his extraordinary deductive abilities are up to any challenge.