Sephy is a Cross: she lives a life of privilege and power. But she's lonely, and burns with injustice at the world she sees around her.
Callum is a nought: he's considered to be less than nothing - a blanker, there to serve Crosses - but he dreams of a better life.
They've been friends since they were children, and they both know that's as far as it can ever go. Noughts and Crosses are fated to be bitter enemies - love is out of the question.
Then - in spite of a world that is fiercely against them - these star-crossed lovers choose each other.
But this is love story that will lead both of them into terrible danger . . . and which will have shocking repercussions for generations to come.