Trainee idol Kim Yi-jin had his crucial debut performance ruined when narcotics detective Seong Han-gyeol stormed the scene chasing a drug dealer. Thinking they would never meet again, they were shocked to discover they were now stepsiblings with no blood relation. Furious, Yi-jin decides to take revenge by seducing Han-gyeol, only to find himself falling for him. Thus begins the heart-racing, borderline forbidden romance between pseudo-siblings.