On a quiet summer afternoon, two teenagers, Lisa and Patricia, decide to pass the time playing with the house phone. However, their innocent fun turns into a dangerous game when they start making random calls and imitating other people's voices. Everything seems harmless until they accidentally contact a man who, unbeknownst to them, is involved in a dark secret.
As they listen to this stranger's conversation, the girls discover that he has just committed a murder. Instead of being frightened, their curiosity consumes them, and they soon find themselves caught in a moral dilemma. As they try to learn more about this mysterious man, the situation escalates, and the game becomes serious. What started as a joke quickly transforms into a cat-and-mouse game when the killer realizes that someone is watching.
Against a backdrop of tension and latent fear, Lisa and Patricia become the unwitting protagonists of a psychological thriller that tests their courage and friendship. As they attempt to escape the looming threat, the girls must confront not only a murderer but also the dark depths of their own morality. In a race against time, they will learn that some truths are better left hidden.