The book is a young adult mystery thriller that focuses on the "origins" of Sherlock’s deductive reasoning and physical skills. About the Author

It provides backstory for the strained but significant relationship between Sherlock and his older brother Mycroft.

(The Red Leech) is the second novel in the Young Sherlock Holmes series written by Andrew Lane. Published as part of a collection authorized by the Conan Doyle Estate, the book explores the formative years of the world's most famous detective. Plot Summary

The novel blends fictional detective work with real historical events, specifically the aftermath of the American Civil War and the fate of John Wilkes Booth.