Liu Chia Liang is kung fu master Chen, tricked and crippled by the villainous gangster and brothel-keeper Tuen (Lo Lieh), who also forces his sister into prostitution. No longer able to practice the martial arts, he becomes a lowly street entertainer, performing with his beloved trained monkey Ah Mao. Tuen's men slaughter the animal, forcing Chen and his petty-thief sidekick Little Monkey (the remarkable Hsiao Hou) into mortal combat with the enemy, the ultimate test of their Mad Monkey style kung fu!