What was supposed to be a normal school retreat quickly turns into a nightmare when Class 2-3 becomes trapped inside their school during a storm. No signal. No escape. No adults. Then every student receives the same notification: [The Mafia Game will now begin.] At first, everyone thinks it’s just a prank. Until the first student dies. Forced into a real-life version of the Mafia Game, students are secretly assigned roles each night — Mafia, Doctor, Police, or Civilian. Every morning, the class must vote on who they believe the Mafia is. If they choose wrong, someone dies. If they refuse to play, someone dies anyway. As paranoia spreads and friendships slowly collapse, fear begins turning classmates against each other. And somehow, in the middle of all the chaos, you keep ending up beside Koh Gyeong-Jun — the cold, violent troublemaker everyone is afraid of. But the longer the game continues, the more you realize something terrifying: The boy everyone thinks is dangerous may be the only person trying to keep you alive.