First English Edition, Advance Proof Copy in original printed wrappers with "Proof." and title at front panel. Extremely rare Hubin listed mystery title to be found in original advance state wrappers. This copy with numerous corrections throughout text in Le Queux's hand, including changes in word choice, spelling, and few complete sentences. Advance proofs of Le Queux, often considered the father of espionage fiction, are uncommon, and with his corrections even more so. Very Good plus, some modest shelf wear, minor loss at spine ends and corners, one page with outer margin corners torn away.