In a world where superpowers are both a gift and a curse, a maximum-security prison holds the most dangerous metahuman criminals ever captured. When a catastrophic event traps a young guard, played by Moon Nam-sook, inside the fortified walls, she must forge uneasy alliances with the very inmates she was tasked to contain. Surrounded by formidable figures like the enigmatic Hong So-young and the volatile Jeon Tae-yeol, she discovers that survival depends on navigating a complex web of rivalries and hidden agendas within the penitentiary's oppressive depths. Directed by Xiaoqing Cai and Cai Dongqing, this high-stakes action thriller plunges into a claustrophobic battle for power where the line between hero and villain is razor-thin. As tensions erupt into explosive confrontations, the guard must use her wits and courage to uncover the prison's dark secrets before a greater threat consumes them all.