With Na-hee exposing her identity, everyone discovers that So-mi's the Mafia, placing Na-hee in danger with her police role now known. Holding herself responsible for her friends' deaths, Na-hee devises a plan to unveil the Mafia even after her potential death. Although clues surface, they are too ambiguous to conclusively identify the Mafia. Meanwhile, the focus shifts to Mi-na as the next target in the voting process.

Everyone corners Yeon-woo as the Mafia because he got wounded. He tries to defend himself, but he gets voted in the end. Da-bum feels relieved, and Jun-hee catches that moment. He confronts Da-bum and tells him not to kill Yoon Seo and Jung-won. Yeon-woo's identity is revealed, and Yoon-seo finds out who the last Mafia is. Meanwhile, Da-bum wants to end the game to avoid being suspected.

The Mafia Game nears its conclusion as more classmates are executed. Da-bum continues to threaten the remaining students' lives. Meanwhile, Jung-won faces a dilemma with her life at stake, and Yoon-seo is unexpectedly exposed to the shocking secret behind the game and the people involved in it.