A society where your performance in school and in life determines your social standing and the performance and behaviour of your family can sway that standing.
Q takes to a new level (but perhaps not that unimaginable) the social tiers of society based on a number of factors that add up to give your "Q" score. A world where everything is scrutinised and tested on a frighteningly regular basis should feel very dystopian and unreal but actually is worryingly familiar in many ways.
The Q system is a repeat of some of the worst incidences of eugenics and widespread human rights abuses and yet those in charge of the system, seemingly derived from a few innocent comments made by the unpopular kids at school, have learned nothing from history and plough on regardless with their bright new society.
When Elen finds that her younger daughter has failed and is moved to a yellow school (the worst case possible) she does all she can to bring her back by deliberately demoting herself to the same status. All is definitely not as advertised as Elen finds out when she reaches Kansas and the yellow school and finds herself stuck in a system that is upheld and run by her husband.
There are a few points in the book where great leaps are made, perhaps in the edit, where I could have done with a bit more detail or background but overall a great premise for a story with plenty of breath-holding moments as Elen fights for her child's rights.