Four Flies on Grey Velvet is a 1971 Italian-French Giallo film directed by Dario Argento. The film follows Roberto, a drummer in a rock band, who begins receiving strange phone calls and being followed by a mysterious man wearing sunglasses. One night, Roberto manages to catch up with the man and confront him, but in the ensuing struggle, he accidentally stabs and kills him.
Feeling guilty and terrified, Roberto tries to dispose of the body but eventually gives up and returns home. The following day, he receives an envelope containing photos of him killing the man, along with a letter demanding a large sum of money. Roberto realizes that he is being blackmailed and decides to seek help from his lawyer friend, who suggests he hires a private investigator to help clear his name.
As Roberto works to prove his innocence and uncover the identity of the true killer, he finds himself being targeted by a mysterious assailant who seems intent on framing him for a string of murders. With his life spiraling out of control and time running out, Roberto must race against the clock to uncover the truth before it's too late.
Four Flies on Grey Velvet is notable for its stylish cinematography, striking visuals, and atmospheric soundtrack, which were all hallmarks of the Giallo genre. The film received mixed reviews upon its release but has since garnered a cult following among fans of Italian horror cinema and remains a favorite of Argento's filmography.