Former thug Choi Mun-hyeok will do anything to protect his younger siblings. When he’s defeated in an underground fight club and sold in an auction to Seo Yeonjin, he reluctantly allows himself to be put on a leash for his family’s sake. Yeon-jin, on the other hand, doesn’t care much for family. In fact, he intends to cause a scandal that will outrage his billionaire father by embarking on a twisted, carnal affair with Mun-hyeok. All Mun-hyeok needs to do is serve Yeonjin well, in work and in bed. However, their passionate encounters might turn into something greater than they bargained for. After all, the line between passion and madness is a thin one…