Sehun, an agent of South Korea's National Intelligence Service, goes undercover as a female stylist in an entertainment company.

His mission: To bust the ion ring that the company secretly operates.

The distraction: He gets assigned as the stylist of Kai, the top solo artist of the company who also happens to be his ex-boyfriend, and who seems to enjoy giving his new stylist a hard time.

What Sehun doesn't know is that Kai immediately recognized who his new stylist really is, and although he's still bitter about Sehun leaving him all of a sudden three years ago with no proper explanation, he couldn't deny to himself that his feelings never really faded away, and all he really wants is for Sehun to love him again.