Christopher Lee returns in this fourth chapter as the evil Fu Manchu , this time has designed a fantastic gadget injecting gorgeous girls (Leni Von Friedl, among others) a venomous poison which reacts in a killing kiss . The beautiful girls are sent to seduce Nayland Smith (Richard Greene replaced Douglas Wilmer) and world leaders . When Nayland Smith is kissed by a death-kiss and he then strolls completely blinded , letting his assistant Dr. Petrie (Howard Marion Crawford) takes the center of attention . A blind Nayland Smith enlists the help an adventurer named Jansen (Gotz George) and an attractive woman (Maria Rhom, married to producer Harry Allan Towers) .

This is a bizarre blending of adventures , thriller and Spaghetti Western . This exciting picture is full of Chinese killers , British adventurers , and Cangaiceiros dressed in Mexican bandits-alike . Weak performance by Richard Greene as Nyland Smith who in previous episodes was best interpreted by Nigel Green and Douglas Wilmer . The villain T Sai Chin stands out as Fu Manchu’s daughter and the murderous bandit Ricardo Palacios overacting as a sympathetic chief Cangaicero . This is the beginning of collaborating between Jesus Franco or ¨Uncle Jess¨ and the producer Harry Allan Towers and to be continued in several movies . Filmed in Madrid and Rio De Janeiro and well photographed by Manuel Merino . Atmospheric musical score by Daniel White , Jess Frank’s usual.

Most critics felt this outing was one of the weakest entries along with ¨The castle of Fu Manchu¨ also directed by Jess Frank with similar casting , plenty of stock-shots and a Z-series style . Christopher Lee (Dr. Fu Manchu), Tsai Chin (Lin Tang) and Howard Marion-Crawford (Dr. Petrie) are the only actors to appear in all five Harry Allan Towers/Fu Manchu films . The best installments resulted to be ¨Face of Fu Manchu (1965, Don Sharp)¨ , and ¨Brides of Fu Manchu (1966, Don Sharp)¨ and the inferior ¨Vengeance of Fu Manchu (1967 , Jeremy Summers) ¨.