Tremendous and glittering, the Space Station floated up out of the Big Dark. Lieutenant Corriston had come to see its marvels, but he soon found himself entrapped in its unsuspected terrors. For the grim reality was that some deadly outer-space power had usurped control of the great artificial moon. A lovely woman had disappeared; passengers were being fleeced and enslaved; and, using fantastic disguises, imposters were using the Station for their own mysterious ends. Pursued by unearthly monsters and hunted with super-scientific cunning, Corriston struggles to unmask the mystery. For upon his success depended his life, his love and the future of Earth itself.