At Seoul Station after sunset, an old man among many homeless people looks like he is devouring another. Soon, the whole street is full of crazy people. Hae-sun, a runaway girl, broke up with her boyfriend who forced her into prostitution. She left the rundown hotel near Seoul Station where they witnessed people being attacked. The attacked people became attackers, and their numbers increased exponentially. The government announced that the whole area was closed. People who were not attacked wanted to escape from the attackers, but there was nowhere to go.