Lee DongHae and Choi Siwon have been best friends since they were children. They found their friendship through music and mutual hardships. Growing up in the slums of Seoul, South Korea, they sing their music anywhere that will accept them. One day, the director of Destiny High School of Performing Arts hears their music and offers them a full ride scholarship. It sounds too good to be true, but never look a gift horse in the mouth.

Park Shin Hye attends Destiny High School and has since lost her interest in music. After losing her mother in a car crash and undergoing painful throat surgery, she isn't sure she will ever sing again. That is until one day she hears the most beautiful song drifting from one of the empty classrooms. When she goes to check it out, the room is empty except for one piece of music. Who's song is this and why does it send a thrill through her the almost feels like love?

Three artists, one song. Who will come out on top when love comes into the picture and friendship is tested?