Taipei descends into absolute carnage when a government ignored virus transforms the population into articulate, sadistic killers who act on every dark impulse. Jim struggles through the streets to reach his girlfriend Kat, while she survives a harrowing subway transit and a nightmarish hospital siege. As the infected stalk the corridors with surgical precision and perverse glee, the couple fights against both the encroaching mob and the monstrous medical theories of Alan Wong. The city bleeds out as the biological weapon erodes the very definition of humanity, pushing the survivors toward a final, desperate confrontation on the hospital rooftop.