Rhapsody in Black

From the back cover of the DAW first edition: "Darkness planet - The planet was a sponge of stone and metal, honeycombed with millions of narrow passages, hidden lightless caves, and scurrying pale colonists who hated the stars and the men who came from them. Somewhere amid the lightless maze there was a newly found treasure - a thing, nobody knew just what, that would make its owner either richer than any emperor had ever dreamed, or give its finder power beyond any imperial army's weapons. Grainger, pilot of the starcraft HOODED SWAN, was down there in the darkness hunting. Nor for himself, but for the unscrupulous men who held his coul in bondage. But the alien second mind that was parasitic to Grainger's owed no other human allegiance. To its inscrutable way of thinking, the potency of the unknown discovery could be a lever to move a universe."