On the eve of World War I, a German agent awaits one last package—containing valuable naval signals—before he prepares to leave for Berlin. A London landlady has a mysterious tenant who is never seen to emerge from his room. A rich elderly woman disappears from her home. The highly confidential plans to build a submarine are missing—though ten pages are found near the body of a naval clerk.
These mysteries and many more are brought to the house on Baker Street where Sherlock Holmes resides. But no case is too tricky for the world's most famous sleuth and his incredible powers of deduction