Yan Yifeng died after suffering a heart attack in a mixed martial arts match against Thai boxer Desri. His death devastated his father, Yan Dongshan, causing him to give up on his martial arts school. 12 years later, Desri returns to challenge Dongshan. Dongshan takes him on, only to be badly defeated. His daughter Yichen and disciples Zhengbing and Shuya decide to come together to help Dongshan revive his martial arts school to take revenge.

一击道馆的颜逸风成功进入到了“国际少年武术大赛”的决赛，对手事来自泰国的强劲选手狄西佛。比赛进行到一半时，逸风毫无征兆地倒下，而且还没有了呼吸。经过查证，逸风是猝死的。东山把丧子之痛迁怒于女儿逸晨和两个徒弟谢正斌和庄舒雅身上，将他们都赶走了，从此不再收徒传授武术。12年后，东山的道馆变成了康乐中心，而让人意想不到的是，成年后的狄西佛竟再度回到新加坡，还不停挑战各大派的武。东山对此不闻不问，没想到狄西佛上门挑衅。东山一气之下，接受了对方的挑战，结果被打趴了，踢馆视频甚至在网上热传。逸晨、正斌和舒雅看到视频后，都纷纷回来，要帮东山重整道馆……

K.O. la más importante escuela de artes marciales mixtas, es abandonada por el director, luego de que su hijo muriera durante una competencia. Ahora su hija y otros luchadores desean devolverle la gloria de los viejos tiempos. Pronto sale a la luz la verdadera causa de la muerte de su hermano.