Secret Agent No. 1 (1970)

The bodies of young girls are repeatedly found in the city, leading Detective Li to suspect a psychopath as the killer. Li's sister, believing the nightclub manager, Mr. Kim, to be suspicious, launches an investigation, but she and Li's girlfriend, Bixi, disappear one after the other. Following Mr. Kim's trail, Li discovers that he is using women's fighting as a lure to sell hallucinogenic drugs.