The purchase, selling, or owning of a gun is banned in South Korea. There are almost zero crime cases involving guns in the country. Things change quickly. Illegal guns, from unknown sources, are brought into the country and gun incidents proliferate.Lee Do is a righteous detective. In the past, he served in the military as a sniper. Now, Lee Do struggles to stop a series of gun incidents and chases after the source of the illegal firearms.Moon Baek is a key figure in the underground arms broker world. He acts like an easygoing person, but he is a person who meticulously plans out his actions and then puts his plan into action. These two men, Lee Do and Moon Baek, hold a gun for their own reasons.