Watch Mr. Big (1978) Official Trailer

Piao resigns from his job as a mechanic in disgust, after the boss grovels to that ubiquitous stock character of HK action movies, a belligerent American. Piao joins a gang and quickly takes over, leading them into a robbery which unexpectedly nets a huge shipment of guns, which "belong" to an associate of the 36th Tong. This event also brings Piao in contact with the sworn enemy of the head of the 36th Tong.