Living in a dystopic future, Leah and her younger sister Rachel are fighting to survive in a world that's becoming increasingly unlivable. Earth's atmosphere has been poisoned by pollution, so each year the government—Terra—holds a contest for all eligible, healthy 16-year-olds. The winners, 100 teens who possess skills that will contribute to Venus's floating biosphere, are sent to the Floating City. Though both Leah and Rachel are talented gardeners, Leah's pollution-induced asthma makes her ineligible. After Rachel is selected for the Floating City, she tricks Terra's medical staff and sends Leah in her place to save Leah's life. Once on Venus, Leah continues to hide her true identity. She is assigned to work in the city's greenhouse where she meets Rose, who awakens something inside her she never knew existed. But when Leah's asthma returns, she's forced to find out whether true love can survive deceit, and if her sister's sacrifice was ultimately worth the price.