Winter, 1977. The sound of the restored college entrance exam shattered a decade of frozen silence.
Ning Xiaoshuang is the daughter of a family branded as class enemies. Her father is a mathematics professor sent away for labor reform, and her mother keeps the family fed by making paper boxes. She works as a temporary laborer at a textile mill, hiding a copy of her father's Advanced Mathematics textbook and secretly working through problems by kerosene lamp, hoping knowledge can wash away her family's humiliation.
Song Weidong is the thorn in the side of the educated youth settlement. A scar cuts across his brow, and his right leg was left disabled after he saved someone. The son of a Tsinghua teaching assistant, he has spent six years in Hongqi Commune repairing irrigation canals by day and covering the dirt with calculus formulas written with a branch by night.
A chance encounter while catching a thief brings together two young people abandoned by their times. He teaches her to solve problems in the snow, and she forges an official seal to get him permission to take the college entrance exam. When Ning Xiaoshuang's father's academic notes are confiscated and burned, and the commune breaks Song Weidong's right index finger, they discover
