Andrew Peel and Julia Washington are a couple of high school nerds who move in different social circles-the former is a goofball geek, the latter is a bookish nerd aiming for valedictorian. One day during a driving lesson gone awry, they have visions of an alien megacity in the sky. Singing to them. Stalking them. Over the next few years, their lives change and their friendship grows as they try their best to determine what is happening. Why is the sideways city only appearing to them? And what does it want?