Cheng Hui (played by Nick Cheung), the outdated Hong Kong boxing champion, became addicted to gambling and was heavily in debt after his boxing career declined. In order to avoid debt collectors, he fled to Macau. In a shared house, Cheng Hui met a mother and daughter. The mother (played by Mei Ting) suffered from mental illness, and the little girl (played by Li Xinqiao) had to go to school and take care of her mother. Cheng Hui and the little girl got along very well. They often dressed up as small animals, rehearsed skits, and made the little girl's mother happy. At the same time, the rich second-generation Lin Siqi (played by Eddie Peng) suffered a family change. His father (played by Gao Jie) failed in business and became penniless. He spent the whole day in the bar. In order to encourage his down-and-out father to start his life again, Lin Siqi signed up for MMA. To this end, he signed up at a boxing club, where he met Cheng Hui, who was working in the club, and worshipped him as a teacher to learn boxing. After several months of study, Lin Siqi won several consecutive games in MMA and became the new boxing champion. Then, he encountered the challenge of another master (played by Andy On), and Lin Siqi withdrew from the competition due to injury. At the same time, the debt collector found Cheng Hui, and during the fight, he accidentally hurt Mei Ting and her daughter. For this, Cheng Hui felt guilty and did not want to implicate others, so he began to retrain his mixed martial arts skills, hoping to win the MMA competition and get the bonus to repay his gambling debts. In MMA, Cheng Hui challenged boxing at the age of more than 40, but was not favored by others. And the opponent he encountered was the new boxing champion Andy On who defeated his apprentice Lin Siqi...