The oldest spacefaring race in the galaxy were the secretive Gallacellans. The most difficult type of planet to explore is the heavy gas giant, the Jovian-Saturnian type planet with which all star systems abound. Somewhere on the storm-ridden unapproachable surface of such a monstrous gas giant an abandoned Gallacellan warship was lying. It was reputed to be armed with the device known to legend as the Fenris weapon. Such stories attract adventurers thirsting for power. Such tales also attract the masters of the Hooded Wan who sought knowledge rather than power. And when they gave orders, Grainger of the double-mind had no choice but to obey. It was up to Grainger therefore to take a little walk where no man had ever gone before--in a hell of nature's making and man's ambitions.