Three young boys walk into a dark, abandoned house and toss a tennis ball down a dark stairway leading to the basement. One of the boys is told to retrieve the ball or he will be considered a sissy. The boys scream at the little blond boy "you're a female!" The boy cries and walks down, and after a scream, a bloody tennis ball is thrown back up. The other two boys run away.Giovanni, a local caretaker, trims the hedges at a local villa as Tony (Michel Sovai) shows Bruno (Andrea Occhipinti) the villa. Bruno is staying there as he composes a score for a thriller film being in post-production back in Rome. Back at the studios, Sandra (Anny Papa), the film's director, shows Bruno the stairway scene (from the opening scene), and discusses her "secret" final reel. Sandra says that she is having Bruno stay in the large, isolated villa to get him into the proper mood to compose the music for the film.At the villa, an unseen person walks outside and slices a magazine photo with a cutter. Just then, Bruno arrives, turns on his tape recorder and records some haunting piano music for the score. A person nearby whispers, and Bruno hears the voice and the sound of the cutter being pushed out. As Bruno looks around, a woman jumps out from a closet (after a spider scared her). The woman introduces herself as Katia (Valeria Cavalli) to Bruno and claims to be a friend of Linda who lives nearby. When Tony calls Bruno and asks him about the lights, he is told that the previous tenant, Linda, liked the dark. Katia asks where the bathroom is and she walks out. Just then, Bruno finds a diary in the closet. He reads it and it mentions Linda's secret. Outside, Katia is chased by an unseen cutter-wielding person. Katie screams to the figure: "I didn't say anything!" Katia is stabbed in the stomach and her neck is slashed.Back inside the house, Bruno rewinds the tape, plays it, and again hears the recorded whispering. He plays it again and hears a words which are "secret", the name of Linda, and "no one must know". Bruno goes outside to smoke a cigarette while a dead Katia is being dragged through the bushes by the unseen killer. Bruno hears a noise in the bushes and goes to investigate it. As he approaches the killer's hiding spot, the cutter is prepared, but Bruno returns to the house when the phone rings. When Bruno answers, the phone only makes a crackle sound as there is interference. Bruno hangs up and sees that he has some blood on his pants. Bruno goes back outside again to the bushes, but by this time the killer is gone and there is blood drag marks on the grass. At Giovanni's house on the grounds, he finds blood on the back steps to his house. Bruno hears the music inside the villa turn off in which he returns and finds the diary with the pages torn out. When Bruno sees Giovanni's front door light come on, he goes to the other house and helps him as he carries a trash bag. Giovanni claims to Bruno that he is throwing away some old newspapers and magazines. Bruno asks Giovanni about the previous tenant Linda, and Giovanni says that he did not know her all that well. A few minutes later, Julia (Lara Naszinski), Bruno's actress girlfriend, arrives at the villa and tells Bruno and her rehearsal was canceled and she was the one who called earlier but something was wrong with the phone line.The next day, Bruno tells Julia about his strange night. After Julia leaves, Bruno goes to the cellar and finds a locked door. Tony arrives at the villa where Bruno asks him about the locked door and Tony says that it contains things that Lind left behind. Bruno asks what Linda was like and Tony says that she was a "normal kind of girl". Just then, Bruno gets a call from Sandra and asks to meet later.Later that afternoon, Angela (Fabiola Toledo) arrives at the villa and tells Bruno that she is looking for her live-in girlfriend Katia who did not come home last night. Angela tells Bruno that Katia came over to get her diary back. Bruno asks about Linda, and Angela says that Linda would let her and Katia come over to swim in the pool there. Bruno tells Angela that she can use the pool whenever she wants. Angela then goes to the pool house to change. Giovanni watches her while she swims. While Angela is diving underwater, she finds the cutter on the bottom of the pool. When Bruno leaves for the studio, Angela walks into the house, while an unseen person, wearing womens high-heeled shoes with a red skirt, blouse, and red-painted fingernails, takes a knife from the kitchen. Angela goes to the upstairs bathroom to change and to wash her hair in the bathtub. As she reaches for the shampoo, her hand is stabbed and pinned to the sink by the kitchen knife. The killer then puts a plastic bag over her head and repeatedly slams her head into the counter, while laughing maniacally. Angela mages to pull the knife out of her hand, but she is placed in the tub and her throat is slit. The killer then begins cleaning the floor and counter with tissues.At the studio, Bruno works and waits for Sandra to show up, which she never does. At the end of the day, Bruno returns to the villa. In the kitchen, Bruno sees that one of the kitchen knifes is not with the others. Going to the upstairs bathroom which is now clean, he finds an empty box of tissues, a cut on the counter, and a bloody piece of torn tissue paper on the floor. In the cellar, Bruno finds more bloody tissues under the locked door. Bruno records himself and talks of possibly uncovering a string of murders, beliving that Angela and Katia are dead.A little later, Sandra arrives and Bruno tells her what happened. Sandra mentions the killer not being able to move the bodies, and Bruno tells of a locked door in the cellar. Sandra says that she knows a Linda, but "it couldn't be her". They go down to the cellar where they find the door unlocked. When they find a large truck in the room which is filled with tennis balls, Sandra says that it must be the Linda she knew. She says that Linda as a child was the basis for the character in her film. They hear someone in the studio above. In the hallway, Bruno is nearly stabbed by a nervous Julia. After they settle down, Sandra leaves. Julia tells Bruno that the play she is appearing in was suspected due to obscenity charges.The next day, Sandra calls Linda and says that she is sorry for the way things turned out between them. She says that she used Lindas story in the movie, but it was mostly fabricated and says to Linda over the phone "I didn't say anything". The unseen Linda merely whispers and hangs up.At the villa, Bruno finds Julia listening to his tape and the two of them argue about the murders since Julia is skeptic that two murders have just taken place since there is no bodies or evidence of any fowl play. When Bruno asks Julia to go with him to the police, but she again thinks that there is no murderer lurking on the grounds. A little later, Bruno goes out and down the street to a payphone where he calls the director of the theater where Julia is working and asks about the charges of obscenity. The director tells Bruno that there are no obscenity charges for it is a children's play, and that Julia left on opening night without an explanation.At the studio, the unseen woman enters the editing room, takes out a film canister and begins to cut up the film reel. Bruno, at that very second, is meeting nearby with Carlo the editor and tries to persuade him to let him see the last reel. When they arrive in the editing room, the killer has quietly sneaked out and left behind the film which is cut to pieces. Back at the villa, Giovanni finds the dead bodies of Angela and Katia in his tool shed, but before he can do anything, he is hit on the head with a wrench. At the studio, Bruno and Carlo splice together as much of the damaged film as they can and watch the scene, which is shown of the two boys taunting the other boy to go down into the cellar, and suddenly during a splice a woman appears in the film with her back to the camera. Carlo says that it is probably the killer.At the villa, Sandra arrives to look for Linda and in the garage she finds a bearly living and bloody Giovanni. Linda jumps up from behind Sandra and wraps a film reel around Sandra and chokes her to death.A little while later, Julia arrives at the villa and enters the garage to find a dead Sandra beside a bundle of film reels. Just when, the garage door slams shut. Julia runs into the house looking for Bruno, and after being startled by tennis balls being thrown at her, hides in a closet in the cellar. She tries to keep the door shut as Linda pushes a knife through the door crack to force it open. Just then, Bruno arrives back at the villa and finding the bodies in the garage, enters the cellar and calls out for Linda. Julia jumps out of the closet and runs. Linda chases after her and stabs Julia in the back, killing her. Linda then runs towards Bruno screaming. Bruno grabs a brick and whacks Linda on the head who falls to the ground unconscious. Bruno exmines Julia on the floor and finds that she is already dead. Bruno walks back up to Linda who rises up with the knife and struggles with Bruno, who pulls at Linda's hair where a wig comes off and Bruno is face-to-face with... Tony. Tony swings the knife at Bruno who twists the knife in Tony/Linda's hand and stabs him with the knife. Tony/Linda falls to the floor and screams out: "I am not a female!" and then dies.In the final scene, Bruno watches the final scene in Sandra's film in its entirely where after the two boys run away after the bloody tennis ball flies up from the cellar at them, a woman figure walks back up the stairs and it is the little boy sent down the stairway... now adorned in a wig and dress. Bruno realizes that the sexually confused and frustrated Tony and invented the persona of Linda and had tried to cover up his secret by killing all those who knew him and his secret idenity.