Kung Fu, the Invisible Fist (1972)

An action-filled suspense story of a Shanghai narcotics and prostitution ring. Ki Tin a Japanese kung fu expert, is sent on a secret espionage mission. He joins forces with Lam San Tai, who heads the underworld gangs. Government agent Li is transferred from Nanking to Shanghai to investigate Lam and his mob activities. Li intercepts Ki Tin's messenger and finds a map of the military forces stationed at Wah Nam. Li confronts Ki Tin and a bloody battle follows.