Four years ago, the idol group Dream Boy disbanded after a career-ending scandal, sending them down the route of failure. In the present, Jaeyoung, who was "Happy" of Dream Boy, struggles to make ends meet delivering food. One night, he hears that Sookyeom, the group's former leader, is passed out drunk at a club and rushes to find him. At the club, Jaeyoung collapses due to photosensitivity syndrome. He is saved by Seungmin, who shares the same stage name "Happy," but unlike Jaeyoung, is now the hottest rapper and producer in the industry. Seungmin then makes him an offer: "You know who I am, right? Let's work on a track together."