Tug Cabot's new apartment has several unique features: first is an invisible roommate named, Brialla. More specifically, she's a smart, fuzzy alien teen with a sense of humor and a serious problem. Then, there's the lady across the hall who has her eye on him, and whose geneticist niece, Neilie, has plans for him.
That might be fun, except for the inconvenient fact that the people Brialla escaped from intend to subvert and conquer Earth without anyone noticing. At the moment, though, their goal is to find and kill her, Tug, and anyone else who learns of their existence.
Involved in a war that no one but him and his small band of friends is aware of, all Tug can do is run to the end of the world, and even to another world, to fight a war that he must win or die. And that's before he learns of Brialla's secret weapon: She can sing.