Angela Russo, a sixteen-year-old girl, is found dead in a river, having been fatally violated with a large blunt instrument. Inspector Di Salvo is assigned to the case and focuses his investigations on St. Theresa's, the exclusive school where Angela boarded. Three of the murdered girl's classmates, Franca, Paola and Virginia (who call themselves "The Inseparables"), receive threatening poems from an individual using the name "Nemesis." Bizarre "accidents" start to befall the girls: Franca is injured when someone causes her horse to bolt and Virginia nearly breaks her neck on marbles left at the top of a staircase. But Di Salvo is determined to find the killer, even if it means using unorthodox methods. He is aided by Angela Russo's little sister Emily, whose helpful clues lead to a boutique owned by a dubious character and a vice ring where "rich influential men pay well for teenage favours..."
Fabio Testi
as Inspector Gianni Di Salvo
Christine Kaufmann
as Christina, Di Salvo's girlfriend
Ivan Desny
as Chief Inspector Louis Roccaglio
Jack Taylor
as Michael Parravicini
Bruno Alessandro
as Di Salvo's Assistant
María Asquerino
as Miss Graham
Helga Liné
as Mrs. Russo
Silvia Aguilar
as Virginia Nardini
Taida Urruzola
as Franca
Tony Isbert
as Max van der Weyden
Fausta Avelli
as Emily Russo
Albertina
as
