In Perugia, a serial-killer is strangling college students. Inspector Martino is in charge of the investigation and has a black and red scarf as the only lead to be followed. He asks the scarf street vendor Gianni Tomasso if he recalls who might have bought the scarf, but the man tells that he cannot remember. Then Gianni blackmails the killer and becomes his next victim. Meanwhile the college students and girlfriends Jane, Daniela, Katia and Ursula travel to an isolated villa to spend a couple of days together during a break from the art history classes of their professor Franz that has befriended Jane. When Jane twists her ankle, Dr. Roberto is summoned and asks her to rest. The student Stefano Vanzi stalks Daniela since he is obsessed for her. Are the girls in danger in the villa? Who might be the killer? 　　 　　译文(3): 在佩鲁贾，一名连环杀手正在勒死大学生。马丁诺探长负责调查，他戴着一条黑色和红色的围巾作为唯一的线索。他问围巾街小贩吉安尼·托马索是否记得谁买了围巾，但那人告诉他不记得了。然后詹尼勒索凶手，成为他的下一个受害者。与此同时，大学生和女朋友简、丹妮拉、卡蒂亚和乌苏拉在与简交朋友的教授弗朗茨的艺术史课上休息时，前往一座与世隔绝的别墅，共度几天。当简扭伤脚踝时，罗伯托医生被召来，请她休息。学生斯特凡诺·凡齐（Stefano Vanzi）跟踪丹妮拉，因为他痴迷于丹妮拉。别墅里的女孩们有危险吗？谁可能是凶手？