"Gallun depicts a struggle between the restored people and the natural living. Life on the asteroids, thought machines, a journey to Mars and a star ship expedition to Sirius are woven into the plot. "PEOPLE MINUS X is packed with action, science-fiction style."--_Detroit Times_ * * * * * _Of special interest to science-fiction readers_-- ACE BOOKS _recommends these exciting new volumes_: D-223 THE 13TH IMMORTAL by Robert Silverberg Was he a fugitive from Utopia? _and_ THIS FORTRESS WORLD by James E. Gunn He brought the skies down upon him. D-255 CITY UNDER THE SEA by Kenneth Bulmer Despots of the ocean bottom. _and_ STAR WAYS by Poul Anderson "Enjoyable, fast-moving, convincing."--_Astounding S.F._ D-261 THE VARIABLE MAN AND OTHER STORIES by Philip K. Dick Five exciting adventures in the future. D-277 CITY ON THE MOON by Murray Leinster A novel of the first lunar colonists _and_ MEN ON THE MOON Edited by Donald A. Wollheim A new anthology of lunar exploration. D-286 ACROSS TIME by David Grinnell Kidnapped into the future! _and_ INVADERS FROM EARTH by Robert Silverberg His lies decided the fate of two worlds. 35¢ If not available at your newsdealer, any of these books may be bought by sending 35¢ (plus 5¢ handling fee) for each number to Ace Books, Inc. (Sales Dept.), 23 W. 47th St., New York 36, N. Y. Order by book number * * * * * _If you've enjoyed this book, you will not want to miss these_ ACE SCIENCE-FICTION NOVELS D-266 TWICE UPON A TIME by Charles L. Fontenay Eternal guardians of the star circuit _and_ THE MECHANICAL MONARCH by E. C. Tubb One extra man could unbalance the world. D-205 THE EARTH IN PERIL Edited by Donald A. Wollheim Exciting stories of invaders from space. _and_ WHO SPEAKS OF CONQUEST? by Lan Wright The galaxy said: "Earthmen, go home!" D-215 THREE TO CONQUER by Eric Frank Russell Only one man knew the Earth was invaded! _and_ DOOMSDAY EVE by Robert Moore Williams Were the strangers impervious to H-Bombs? D-199> STAR GUARD by Andre Norton "Fast-paced and good reading."--_Saturday Review_ _and_ THE PLANET OF NO RETURN by Poul Anderson The first--or the last--on that new world?