For today’s teenagers the mid-20th century really is history, and the attitudes of that time are alien to their lives. Young people today are exposed to such a range of cultures and people that segregation (South African apartheid or the Jewish ghettos) can seem unimaginable. Yet even a cursory glance at the news reveals that it is perilously real for some, and not just those in foreign lands.

This is why Marjorie Blackman’s award-winning teen novel is so unsettling. It tells of a divided society with two groups. The Crosses are the lucky ones: born into privilege and wealth. They run the country and have the best funded schools. But the Crosses couldn’t function without the other half – the noughts. The noughts are the bottom half of society. Their purpose is to work for Crosses and to keep the country ticking over. They are suppressed at every opportunity. This is segregation taken to the extreme: and it doesn’t work along the lines you might think it does.

At the start of the story 13-year-old Sephy (a Cross) is secretly continuing a childhood friendship with Callum (a nought). This is a friendship that seems to be on a path to self-destruction as their feelings for each other grow. Fuelled by the growing uprising among noughts and the Liberation Militia the two teenagers are destined to be pulled apart.

Blackman presents many echoes of the past: America in the 50s, South Africa under apartheid, and even the IRA of the 70s and 80s. Add to this some inspiration from Romeo and Juliet and you have a novel that will challenge the way you view the world