In the 1980s, Cheng Hai, the top expert in precision technology, stayed as chief engineer at the struggling Hongxing Machinery Factory to repay his mentor’s kindness and assist the young factory director Zhong Lin. Over three years, he braved countless hardships against all odds, turning Hongxing into a local industry leader. But on the day he led his R&D team back to the factory, he found himself replaced by a new college graduate. With only seven days left until his three-year promise to support Zhong Lin expired, he left resolutely once the term ended. Later, Zhong Lin realized Cheng Hai was gone for good, was consumed by regret, and tried to win him back—but they had already drifted apart, strangers to each other.