The story is about a small group that are doing a secret business where they help people to revenge on the people who have been hurting them. A lot of people who come to them are already become the victim of murder, torture, etc. In this K-Drama series, you're going to find a lot of scenes that show them fighting with weapons and a lot of blood. So make sure you're not afraid to see blood. It's become interesting when there is a case that involves their people during the mission. The revenge of each case is different so there is lot of way to revenge.