To pay for his sick younger sister's treatment, Shen Yanzhou falls into crushing debt. One rainy night, while fishing, he catches a strange golden-scaled koi. Despite his family's desperate poverty, he still chooses kindness and releases it. The koi is actually Su Huanqing, the river spirit of Qingxi, who takes human form and comes to the Shen family to repay his kindness. With her help, the family's fortunes gradually improve, his sister's health recovers, and the two begin to fall for each other. Zhao Shichang covets the river spirit's power and recklessly damages Qingxi, throwing the river into turmoil. To protect the people, Su Huanqing sacrifices herself to repair the river's spiritual veins, causing her physical form to disappear. A year later, as Qingxi regains its vitality, she returns through the river's spiritual energy, allowing Shen Yanzhou and his family to reunite in peace.