Sephy (Masali Baduza) and Callum (Jack Rowan) rekindle their childhood friendship following a chance meeting. She is a Cross, born into the ruling class and an elite family, whilst he is a Nought, a second-class citizen. Amidst rising tensions between Noughts and Crosses, Sephy and Callum's worlds collide when they begin a romance, forever changing the lives of their families, which have until now, been separated by power and prejudice.