“Everyone dies one day. Either today, or tomorrow.” I-nan(SHIN Hyun-joon) is Joseon’s greatest assassin, also called ‘Salsu’, who carries out missions to eliminate his targets. When he discovers he has a heart condition he has to put his violent career aside to go on a journey to find the herb that can cure his heart. Soon, the hunter suddenly becomes the hunted when he discovers there’s a bounty on his head. He is forced to hide in a small town, but when an area’s gang barges in, I-nan has no choice but to take his sword and accept his last deadly mission.