Dario Argento's 1971 feature Four Flies on Grey Velvet is the final film in his "Animal Trilogy", which began with The Bird with the Crystal Plumage and The Cat o' Nine Tails. Another genre notable, Luigi Cozzi served as assistant director. Due to some disagreements over music selections, this would be the last Argento film scored by Ennio Morricone until the 1990s.
Italian film favorite Bud Spencer, plus Americans Mimsy Farmer and Michael Brandon top the films cast. It was picked up by Paramount Pictures for it's United States release but little was done with the film in the U.S. after an initial run.
The plot is convoluted, perhaps a bit too complicated, but overall Four Flies on Grey Velvet rewards a viewer with well shot color saturated and outstanding cinematography (most noatbly what may have been the first use of high-speed camera equipment to film the path and trajectory of a bullet), as well as heaps of Argento's "edge of your seat" cinema. The scene where a woman finds herself locked inside a walled park after closing and is pursued relentlessly stands out for it's memorable and rapidly escalating tension.