Who is the new Jack the Ripper holding Rome in a grip of terror? American author Tony Musante knows he's witnessed a vital clue to the chilling conundrum - but what is it exactly? Dario Argento's giallo trendsetter (giallo, or "yellow", being a term for all Italian thrillers more concerned with the modus operandi of the bloody murders than their whodunnit aspect) is a glossy, stylistic, cosmopolitan and jagged mystery firmly entrenched in Hitchcockian paranoia. A seminal work, it shows Argento's visual flair for horrific set pieces and introduced the trademark themes he would develop in such subsequent violent nightmares as Suspiria and Opera.

An American writer living in Rome witnesses an attempted murder that is connected to an ongoing killing spree in the city and conducts his own investigation, despite he and his girlfriend being targeted by the killer.