When Hyeonu moves into Terrarium Apartments, the place seems idyllic—until he witnesses a man plunge from the building across his window. The residents dismiss the victim as a “misfit”, and Hyeonu soon notices their unsettling, scripted routines. Beneath the cheerful facade lies something far darker: a community that demands conformity and punishes defiance. As the walls close in, Hyeonu realizes that once you enter Terrarium, leaving may no longer be an option.