On a tiny world far out in space, a boy and girl listen to the stories their parents tell of their home planet, Earth, where, difficult as it may be to imagine, the sky is blue instead of black, the ground is covered with something called grass, and everyone must keep his feet on one surface! Of all the things they learn about Earth, one fascinates the children most; and when, at last, they get to travel there by rocketship, they know exactly what they are going to do…