Inside the sterile white walls of New Seoul, it's perfect. The basics - food, shelter, clothing, water, health care - aside, everyone's always entertained: either by super-musicians called Idols, or by the gravity-defying sports superstars called Boarders. Erica Carter - a half-Korean, half-British girl living in New Seoul - has no reason to doubt the perfection of her society. After all, her older brother Sam is one of the most popular Idols out there.

But there's a reason why "utopia" comes from a word meaning "nowhere" - and nobody seems to know that better than Lee Changseob, a mysterious Boarder who she goes to school with. As much as he wants to show Erica the world outside of the walls, there are two things in the way: exactly how stubborn Erica is, and Rome, an infamous "bad-boy" idol that solely wants Erica's heart.