Twenty-two years ago, Lin Chuan gave up his chance to be rescued in a flood so that his younger sister could survive, and the siblings were separated forever. Twenty-two years later, his sister has become a doctor and is still searching for him, unaware that the hospital's reclusive laundry worker is none other than her gravely ill brother. An old harmonica and three familiar knocks gradually reveal his hidden identity. Brother, you saved me back then. This time, let me take you home.