Lee Chang was an undocumented immigrant leading a moderately content life, earning just enough to get by at his workplace. One day, a horrific event strikes his restaurant: everyone suddenly dies simultaneously from elevated cranial pressure. Yet, Chang experiences a bizarre phenomenon: despite clearly being there at the moment of the tragedy, everyone ignores his presence and walks right past him. Amidst this chaos, his thoughts turn to Yoo Hwi, a man he encountered by chance just before the incident. Hwi was someone who had supposedly died years ago, yet Chang clearly spoke with him and saw that he was alive... Triggered by this event, "incomprehensible" occurrences begin to plague Chang's life without end.