Ecological designer Lin Ye is swallowed by a mysterious giant flower, awakens inside the town heart flower of the alien Hecheng Town, and is recognized as the new town mayor. The town is composed of living plants, yet trapped by the ancestral rule that "ancient seeds cannot be altered" and the Sang family's grain monopoly, leading to gradual decay. Lin Ye unlocks new uses for ancient seeds, renovates dwellings, opens up root paths, and revives the market, making the town glow with new life. He is the "alien symbiosis" person sought across boundaries by the old mayor, and his return path is bound to the town's entire grain pulse. Facing the Sang family forcing him to relinquish power and the Plant Law Department threatening him with the lives of a hundred cities, he gives up his close-at-hand return path, shatters the town seal, and saves the hundred cities. But black thorns have already invaded Earth along the return pulse, and his home has become a new battlefield.