Contra-terrene matter—seetee as the astronauts call it—is the most dangerous substance in the universe. Reversely charged, when brought into contact with even the most stable of normal material, it will instantly disintegrate with a 100% energy diffusion. So when Cap Kennedy’s scout vessel, Mordain, brushed against a cloud of seetee dust that was being gathered and moved by unknown ships, it was not only a narrow escape for Cap and his friends but signaled an emergency of the highest urgency. Because such a swarm could cause the destruction of an entire solar system—and ther was reason to suspect that its ultimate target was our sun and all its planets—including particularly the Earth.