Cheol-min (So Ji-sub) was originally an excellent boxer, but now he makes a living by delivering water during the day and watching the night. On the first night of his watch, Cheol-min met the beautiful and sunny girl Jinghua (Han Hyo-joo). Unfortunately, Jinghua's eyesight is gradually deteriorating and she will become blind if she continues to develop. The silent Cheol-min slowly opened his heart in front of Jinghua, and the two fell in love. It turns out that Cheol-min is an orphan who once went astray and became a thug and was imprisoned. Now Cheol-min is determined to start over, embark on a boxing career again, and realize the future he and Jinghua have designed step by step. However, Jinghua's eye disease is getting worse and worse, and she can't wait for them to slowly realize their dreams. At the same time, Cheol-min discovered that the car accident that caused Jinghua's eye membrane to be damaged was actually related to his own mistakes that year. The strong sense of guilt made Cheol-min decide to take the risk of participating in an underground boxing match, just to raise medical expenses for Jinghua as soon as possible. Can Jinghua regain her sight? Can Cheol-min live and reunite with Jinghua?