Chiara is convinced that her husband is cheating on her, but the certainty exists only in her mind. For this reason the woman cannot help but control him constantly, thus entering into endless paranoia. The object of her frustration is her new neighbor Manuela, whose life she makes unbearable with constant stalking, causing her to fall into fear and desperation. Manuela tries to talk to the people close to Chiara — her mother-in-law, her husband himself — and the police, but no one is able to grasp the warning signs of a tragedy that will result in a brutal murder.