In the 1980s, Ma Ding grew up in the hutongs of Beijing with three sworn brothers. On the eve of their high school graduation, an incident triggered by Ma Ding fractures their bond. With youth's end, he drifts into obscurity abroad. Years later, now a vice president of a listed company, Ma Ding is diagnosed with a brain tumor. Preparing to face death alone, a lingering attachment he cannot sever pulls him back. He returns to resolve old grievances and reclaim lost friendship. The four middle-aged brothers embark on a new venture together. As their lives transform, the embers of their past camaraderie slowly rekindle, reigniting Ma Ding's will to live.