This book is based on the Columbia Pictures 1966 movie, by the same name.
It all begins when Ellery Queen receives a manuscript that appears to be a genuine Sherlock Holmes novel written by John H. Watson, M.D. Where did it come from? The manuscript itself tells the long-concealed story of how Holmes stalked Jack the Ripper -- and discovered who he was! Now you can follow Ellery Queen -- the logical successor to Sherlock Holmes -- as he literally follows the greatest detective of them all. The story of "Sherlock Holmes vs. Jack the Ripper" is presented with the full approval of the estate of Sir Arthur Conan Doyle, and is a legitimate addition to the Holmes canon.

The film was then novelized by Ellery Queen and Paul W. Fairman. The framing story was written by Ellery Queen and the novelization was by Fairman. Several plot points were altered for the novelization.