'We reap and we thresh; grain for half the world. We are the Grain Kings raised of old.' They call them the Grain Kings. Gigantic mechanical monarchs of the wheat-bearing plains that were once the frozen Alaskan wastes. Whole eco-systems in themselves, they can supply the food so desperately needed by the teeming millions of our overpopulated planet. But even now, as the whole world waits in hungry suspense, the great powers battle for control of the prairies and two competing combine harvesters find they are heading on a course of collision. A collision with catastrophic consequences - not only for the hundreds of crewmen aboard each massive machine but for the future survival of all mankind.