The time: just after the Chinese Revolution. The place: Northeast China, as Japanese invaders start to infiltrate. The situation: a vicious judo expert sets out to prove that Chinese are the "sick people of Asia" by killing all their best martial artists in corrupt, dangerous tournaments. To save his son, the head of the Ping Pai Boxing Institute sends to the mountain hideout of the master fighter Red Butterfly. There's only one thing which will set things right: the powerful Thunderbolt Fist kung-fu technique!