A case of the flu quickly morphs into a pandemic. As the death toll mounts and the living panic, the government plans extreme measures to contain it.

Follows Rim Chul-ryung heading back to South Korea in pursuit of a brutal and secret criminal organization. He teams up again with Kang Jin-tae, who volunteers to work with the North Korean in order to get back on the investigation team after a mistake landed him in the cyber crime department.

When a crime organization from North Korea crosses borders and enters South Korean soil, a South Korean detective must cooperate with a North Korean detective to investigate their whereabouts.