High-school underdog Yuan helps a homeless man who turns out to be Huang Jun, a once-great warrior. Yuan and his buddy Ah-yi become Huang`s disciples, learning kung fu to right the wrongs. But their newfound powers are tested when Huang`s former disciple, Lan Jin, awakens as a demon king after 500 years, threatening the city with bloodshed and leads Yuan to uncover the big secret behind "kung fu".