Lee Changsoo is a bodyguard who was disciplined and removed from his job after an accident. However, he is offered a chance to return to his job if he performs well as the temporary manager of the company's top idol group, Luminous, until a new manager is found. Changsoo coldly accepts the opportunity, but it doesn't take him long to realize that the girls are uncooperative and landmines waiting to explode at any moment... Will Changsoo make it back to his job as a bodyguard in one piece?