Kim Sun-woo is an enforcer and manager for a hotel owned by a cold, calculative crime boss, Kang who assigns Sun-Woo to a simple errand while he is away on a business trip; to shadow his young mistress, Heesoo, for fear that she may be cheating on him with another, younger man, with the mandate that he must kill them both if he discovers their affair.

After long and grueling hours immersed in brutal crime investigations, lead detective Choi Young Jin must face the particular horrors of singlehandedly raising her daughter Ha Eun. Any way you look at it, Young Jin’s got her work cut out for her, but it’s only a matter of time before her professional and personal worlds collide in new and disastrous ways.