This is an unfinished [Shaw Brothers] production entitled THE NOCTURNAL KILLER. It's possibly an aka for the above mentioned THE LITTLE POISONOUS DRAGON. It's just one of many unfinished films that were started at Shaw's and abandoned for whatever reason. With between 40 and 50 movies being scheduled throughout 1971 and 1972, some productions were scrapped, or morphed into an entirely different picture. Curiously, the plot and Shi Szu's attire appears similar to HEROES OF SUNG (1973; it was filmed under different titles as well), a film that did starred the actress and Lo Lieh, but not the Taiwanese actor, An Ping. - coolasscinema.com, Dec 2010