This is a classic science fiction novel by Marion Zimmer Bradley. This work tells the story of the Terran Empire and their quest to maintain a peaceful rule. However, on the planet Wolf something is afoot. They enlist the services of Race Cargill of the Terran Secret Service, and he goes undercover on Wolf to find the source of the problem. His mission doesn't go as planned and he becomes involved in a blood feud, but this leads him to the secret of THE DOOR THROUGH SPACE. This work is part of our Vintage Sci-Fi Classics Series, a series in which we are republishing some of the best stories in the genre by some of its most acclaimed authors, such as Isaac Asimov, Harry Harrison, and Robert Sheckley. Each publication is complete with a short introduction to the history of science fiction.