Kim Hyun Joong is the leader of the biggest mafia ever. His four sisters formed they're own little gang and they all live together. They harbor all on the run gangs and mafias. Five undercover agents enter the house posing as a gang known as big bang. But when they're leader Gd begins to fall for one Hyun Joong's sisters, he begins to find complications with completing his job. Will he be able to keep it from her or get found out and killed?