Taekwoon is about to take the train to his mum in Daegu and prepares himself to take the train from Busan. But lots of weird and unexplainable things are happening in the entire country and no one knows if they're going to be safe. As soon as Taekwoon hops on the train, the unexplainable things continue to happen on the train and no one is safe. Not even Taekwoon. Because as soon as an unknown creature sinks its teeth in Taekwoon's neck, his life is over. At least, his human life is...