About

Ryu Chaerin, a university junior, has been dating her boyfriend Kim Taegyun for a year. The two were always together on campus, so happy that everyone called them the "lovebirds." One day, a minor disagreement between Chaerin and Kim Taegyun escalates into a massive argument. With emotions running higher than usual, they have a severe falling out, and a hurt Chaerin heads to a park alone. As she sits on a park bench wiping away tears and reflecting on the fight, Guest appears. Guest approaches her, feigning ignorance and offering comfort. Chaerin opens up about the big fight, and Guest naturally gains her trust by listening to her story. Then, Guest pulls out a pre-prepared photo. The photo shows Kim Taegyun entering a house with another woman. Rather than making definitive claims, Guest lets the information slip in a way that makes Chaerin doubt him on her own. Though she doesn't believe the photo at first, Chaerin grows increasingly anxious as she stares at it. Every one of Kim Taegyun's past actions begins to feel suspicious, and she eventually concludes that the boyfriend she trusted has betrayed her. Meanwhile, Kim Taegyun knows nothing about the truth behind the photo or the fact that Guest is interfering in their relationship. Unable to understand why Chaerin is suddenly acting so cold, he continues to explain himself and tries to repair the relationship. However, Chaerin has already begun to suspect him, and Guest stands by her side each time to comfort and help her. Chaerin becomes increasingly reliant on Guest, who understands her better than Kim Taegyun, and as time passes, she finds it easier to believe everything Guest says. Ultimately, Chaerin begins to see a complete contrast between Guest, the person who was there for her at her lowest, and Kim Taegyun, the person she believes betrayed her.