Harry Bittering and his family are among the first thousand Earthmen to move to Mars for the purpose of colonizing it. Yet Bittering feels out of place in his new home. His uneasiness is so profound that he wants his family to return with him to Earth. He has decided that Mars is meant to be inhabited only by Martians. When a war on Earth destroys all of Earth's space ships and prevents Bittering's return, he determines that he must build a ship for himself if he is ever to return to Earth. In addition, he has noticed subtle changes occurring on Mars: roses turn green, his cow grows a third horn, and lawn seeds sprout purple instead of green. Bittering wants to leave Mars before strange things also happen to him. However, his space ship is never used, for the Bitterings as well as the other Earthmen also begin to change. Their color, their bone structure, their complexion, and even their language change. In short, they become Martians. Five years later, the war on Earth ends, and a new ship travels through space, its mission being to save the Earthmen stranded on Mars. Much to the surprise of the rescue team, no Earthmen are to be found — only Martians, who have a great affinity for the English language.
Bradbury transports his readers to a fictionalized world of Mars in this story. He employs sun, fire, and water imagery to describe the changes that occur on Mars. Fire imagery describes the changes that take place in the houses. The air "burns" them, warping the boards out of shape and making them no longer Earthmen's houses. The sun burns the Earthmen's skin almost black, and Bittering himself feels his flesh melt in the hot and liquid air. Water completes the process of change as Bittering lies in the Martian canal water, convinced that this water is eating his flesh away until only his skeleton will be left. He senses that eventually the water will continue its work, evoking a change upon him as it metamorphoses his skeleton. Finally, all the material trappings that are so important to Earthmen are sluffed off, transforming the Earthmen into Martians. The regeneration is complete. This story is similar in setting and subject matter to many of Bradbury's stories contained in The Martian Chronicles.