Roberto Tobias (Michael Brandon) is a musician in a band. One night, after a rehearsal, he sees a man that appears to be stalking him. He follows the man into an abandoned theater and confronts him. The man pulls a knife. In a struggle with the man over the knife the stalker ends up stabbed. Someone in the balcony area photographs the stabbing. For days later Roberto finds pictures and threatening letters from someone who seems to be blackmailing him but no specific blackmail happens. So far all that the blackmailer has done is torture Roberto mentally.

When Roberto is attacked in his own house the maid, Amelia (Marisa Fabbri), realizes who is responsible and tries to blackmail the stalker. The stalker kills her. By now Roberto has told his wife, Nina (Mimsy Farmer), everything that has happened. He then talks to his friend Godfrey (Bud Spencer). Godfrey, or “God” as Roberto calls him, recommends he hire a private investigator, a very gay Arrosio (Jean-Pierre Marielle), to check around.

The man Roberto killed, Carlo Marosi (Calisto Calisti) turns out to be alive and not happy with what he was paid, especially considering the death of the maid. He tries to blackmail the killer. Carlo is the next victim. Nina's cousin Dalia arrives to stay with Nina and Roberto. Nina decides she can’t handle staying at the house with a stalker and murderer around. With Nina gone, Roberto and Dalia end up having an affair.

Arrosio turns out to be a better detective than even he figured since he admitted has never solved a case before. This time, he figures out who the killer is but the killer has also figured out that Arrosio’s streak of failure has been broken. Arrosio finds out his suspicions are correct when the killer is revealed just before killing him. The next victim is Dalia but this time the police want to try an experiment. They want to use optography to produce a picture of the last thing Dalia saw before dying. The image they create is blurry and on a grey background. One of the technicians says it looks like four flies on gray velvet.

“Four Flies on Grey Velvet” AKA “4 mosche di velluto grigio” was released in 1971 and was directed by Dario Argento”. It is an Italian crime mystery thriller and a giallo. It is the third and final film in what is referred to as Argento’s animal trilogy. The other two being “Cat O’ Nine Tails” 1971 and “The Bird with the Crystal Plumage” 1970. The movie is not Argento’s best or his best known film but it is still fascinating.

There are threads of humor throughout the film and there were a couple times that I outright laughed. Some of the characters like the gay detective and the Professor character, played by Oreste Lionello, who God has keep an eye on Roberto’s house are quite satirical and downright funny. The entire scene that takes place in the “Fifth International Exhibition of Funerary Arts” is a total hoot.

Titles for giallo are, if nothing else, inventive. The title for this one is based on a pendant that the killer wears that, when swinging, looks like four flies on grey velvet. The police use of optography to try to determine who the killer was is the plot point that brings the title to the forefront. It is a stretch at the very least.

Although the movie is not a masterpiece there was enough that was unusual and clever that made it interesting. The plot was a little thin however there was enough meat that made me want to find out who the killer was and what was done to tie up all the loose ends.

Optography is a process that is supposed to be able to discern what a person sees before they die. It is the belief that the eye records or remembers what the last image was imprinted on the retina before death. The supposed science was a big thing in the late nineteenth and early twentieth centuries. The concept was used as a plot devise in many murder mysteries despite being debunked over and over. Much of the work in investigating the theory was done by German physiologist Wilhelm Kuhne. Kuhne did experiments on many animals trying to refine the process. The most he managed to do, with certainty, is to kill a bunch of animals so he could inspect their eyeballs.