An alien visitor arrives at an observatory on the moors of Scotland. An ostensibly friendly alien acts as an advance scout to lead his civilization from its dying planet, to Earth. His advanced civilization was able to alter its planet's course to intersect with the Earth, "through scientific degravitation" yet for some reason, was unable to keep it from freezing in its original orbit, and seemed incapable of designing a practical spacesuit. For some other unexplained reason, the fate of his entire race is entrusted to this single scout.