North Korean detective Rim Chul-ryung returns to South Korea while chasing a brutal, secret criminal organization. To pursue the case, he joins forces again with South Korean detective Kang Jin-tae, who sees the assignment as a chance to return to the investigation team after a mistake left him in cyber crime. Their case grows into an unpredictable international operation involving South Korean, North Korean, and American detectives, each with their own reasons for taking part.