After a biking holiday in Yunnan province, China, Lin Siqi, the son of a wealthy businessman, returns to Beijing and bumps into an old friend, Chen, who is enjoying some conspicuous spending after his father died and left him a fortune. In Hong Kong, meanwhile, Hong Kong taxi driver Ching Fai, aka "Scumbag Fai", a former boxer and ex-con with gambling debts, flees to neighbouring Macau and gets a menial job at the gym of old friend Tai-sui. He rents a room in the flat of Wang Mingjun, a Mainlander who has a 10-year-old daughter, Leung Pui-dan. Mingjun still suffers from depression, after a nervous breakdown when her husband left them for another women four years ago, and Ching Fai slowly becomes attached to her and the mouthy Pui-dan. Meanwhile, Siqi has washed up, penniless, in Macau with his father, who has lost the will to live after being bankrupted by a stock-market collapse. Finding work as a manual labourer, Siqi decides to enter the forthcoming Golden Rumble MMA Championship, which has a purse of HK$2 million. With some experience in taekwondo, he enrols at the same gym where Ching Fai happens to work, in order to learn MMA. Siqi also bumps into a former Mainland girlfriend, Keke, who tells him she now has a wealthy new boyfriend. After Ching Fai by chance helps out Siqi one night when the latter's father turns violent, Ching Fai agrees to help Siqi with his MMA training, even though the championship is only 10 weeks away. However, Ching Fai, despite being 48, also harbours a secret desire to compete for the prize money which he so desperately needs.