In Perugia, the murder of several university students leads to a manhunt for a masked killer with a psychosexual disorder who uses red-and-black foulards to strangle his female victims before mutilating their bodies. When a wealthy student named Dani vaguely recalls having seen someone wearing such a scarf, she becomes the target of the mystery killer and, at her philandering uncle's suggestion, invites three of her girlfriends to stay with her at her family's remote country villa in Tagliacozzo. However, the isolated cliffside villa offers no protection from the killer, who has meanwhile run over the blackmailing street vendor he buys his scarves from. A local peeping tom and then Dani's impotentstalker go up to the villa, only to be ruthlessly killed too. One of the girls, Jane, sprains her ankle and a local doctor gives her a sedative; as such, she is asleep when the killer forces his way into the villa and kills her three girlfriends. Jane wakes up the next day only to silently witness the unidentified killer dismember her friends' bodies. Having disposed of the corpses, the killer locks up the villa and departs, inadvertently leaving the injured Jane trapped inside. Later on, having realized that Jane is alive in the villa, the killer silently returns and reveals himself to her. The killer is Franz, an art history lecturer Jane had befriended. He is a psychopathicmisogynist as a result of a childhood trauma when he witnessed his brother fall to his death as he was trying to fetch a little girl's doll at a cliff's edge. Franz tells Jane that his first two victims had seduced him into a threesome and then blackmailed him. He had continued his killing spree in order to cover his tracks. As Franz proceeds to murder Jane to ensure he is never caught, the doctor shows up and, after a struggle, Franz falls to his death.
George Anderson of the Pittsburgh Post-Gazette deemed the film "another display of softcore sex and seamy violence that might better have been kept abroad." Joe Baltake of the Philadelphia Daily News wrote: "Blood flows freely and limbs detach easily, in Sergio Martino's Torso, a disagreeable Italian import withnot surprisinglylittle to recommend it." The Los Angeles Timess Linda Gross wrote that the film was a "lazy suspense movie" with a "disjointed and loose" screenplay. The extended cat-and-mouse villa scenes between the killer and the final girl in the film's last 30 minutes have led to Torso being retrospectively recognised as a "proto-slasher film". Quentin Tarantino showed his print of the film at the 1999 QT-Fest and fellow filmmaker Eli Roth has cited the film among his favourite gialli and an influence on Grindhouse and . PopMatters gave it a 7 out of 10 rating, while Slant Magazine said it "pales next to director Sergio Martino's more inventive sleaze-thrillers ".
