There were five aboard the orbiting wheel in the sky—an American, a Russian, a Frenchman, an Englishman, an Indian. Their job was to keep watch—over each other. The Wheel held enough fission-fusion bombs to blast all of Earth but the five watchdogs saw to it that those bombs remained stored, a potential threat and no more to aggressors below. And then Gregson and Lal discovered the alien spaceship moored outside Supplementary Airlock One. It looked like no spaceship they had ever set eyes on bef