In a frame story, a rich couple sailing alone in space, Jinn and Phyllis, rescue and translate a manuscript from a floating bottle. The manuscript was written by journalist Ulysse Mérou, who in 2500 was invited by wealthy Professor Antelle to accompany him and his disciple, physician Arthur Levain, to Betelgeuse. Because they travel close to the speed of light, time dilation causes centuries to pass on Earth during their two years in transit. They land their shuttle on a temperate, lushly forested planet which they name "Soror" (Latin for "sister"). They can breathe the air, drink the water and eat the fruit. Attracted by a woman whom they call Nova, they swim below a scenic waterfall. She is frightened by their pet chimpanzee, Hector, and strangles it. Her tribe, who exhibit the behavior of dumb animals, wreck the newcomers' clothing and shuttle.