Seo Na-young, a timid and ordinary college sophomore, joins the board game club 'Playmate' with a pure heart. Kind seniors, a warm atmosphere—everything seemed perfect at first. But one day, the club reveals a completely different face. "The loser of the game must perform a penalty." At first, it was just light-hearted fun. However, as the games repeat, the penalties cross the line more and more, and Na-young confronts desires she didn't even know she had. Even though she wants to run away, she soon finds herself waiting for the next game. And she realizes: once you become a player, you can never step off this game board.