Stories 21 - 30 Summary

"The City" is a mechanized city built by an alien civilization as a trap for Earth explorers. In the story a group of Earth explorers lands, begins exploring the city, and is wiped out as an automated act of revenge. The dead men's brains are replaced with mechanical objects and they are animated by a fusion of advanced robotics. The automated crew boards their rocket for the return trip, loaded down with disease bombs. In "The Fire Balloons," a group of Christian missionaries travels to Mars to bring religion to the newly-colonized planet. Upon arrival they learn that there are two races of intelligent Martians—one is apparently very much like humans but nearly extinct; the second is a type of brilliant floating light. The missionaries, led by Father Peregrine, contact the floating lights and discover them to be nearly-perfected...