Sephy and Callum have been best friends since childhood, and now they are older and they realise they want more from each other.
But the harsh realities of lives lived in a segregated society are beginning to take their toll: Callum is a nought - a second-class citizen in a world dominated by the Crosses - and Sephy is a Cross, and the daughter of one of the most powerful men in the country.
The barriers they would have to cross to be together at first seem little more than minor obstacles to the two idealistic teenagers, but soon those barriers threaten not only their friendship but their lives.