Desperate, lost, the machine men of Zor took off on the most perilous mission they had ever faced-against a foe that could not die!ExcerptSince reaching Zor, this new expedition had embarked upon a roundabout direction, which Professor Jameson expected would ultimately lead him back in the direction of his own world and the nearby system of Sirius, where the strangely evolutionized descendants of humanity had fled millions of years ago when Earth had become chill and the sun had grown subdued. As the present narrative opens, however, we find them upon the third world of a system comprised of five planets.Orange sunlight streamed down upon the hull of the spaceship, moored upon a plain of waving, yellow grasses. The sun was not far above the horizon, and was slowly sinking. Fantastic animals and birds uttered strange cries and noises, but showed little curiosity in regards to the machine men.Professor Jameson and 744U-21 stood and watched machine men flying in from different directions on their metal wings. They were about to leave this third world of the orange sun. There were two outer planets in opposition at their present orbital phases, and it had been the agreed design of the machine men to explore these nearer worlds before proceeding to those closer the sun."I have a strange curiosity, developed since we came to this third world, to see what the second planet is like," said the professor. "Now that we are about to leave here for the fourth and fifth planets, this curiosity seems to have grown stronger.""A coincidence," 744U-21 observed, "for I feel the same way, but it is more logical to visit the outer worlds first."The professor was inclined to agree with him. It was strange that they should both become so unreasonably obsessed with the same idea, 6W-438 and 8L-404 approached."I think we are making a mistake going to those outer worlds before we have explored the worlds closest the sun," said 6W-438."What makes you think that?" 744U-21 asked."I don't know. But SL-404 thinks the same, and so do others with whom I have talked."