There is a strange disease that is taking lives of ten year old children. Soon, most of the kids are gone and those who are left are discovered to have special powers and are taken into camps for testing.
Ruby is one of those children and she gets taken to a camp Thurmond. Upon arriving, the children are tested to determine what category they belong to: green, blue, yellow, orange, or red. On this scale blue children are the most harmless and red are most dangerous. Ruby manages to convince the doctor that she is green when in fact she is an orange. Life at Thurmond for these children is grim, since they are treated as less than human. Ruby's power includes manipulating, mind controlling other people, and seeing their thoughts; she accidentally wipes out the memory of her only friend at camp.
The Thurmond eventually becomes a place for greens and blues only and it is believed that the rest are executed. The camp controllers find a way to bring the rest of reds, yellows and oranges out of hiding by using something called a White Noise. On one of the occasions where they use this Ruby is under suspicion of being an orange and one of the doctors at Thurmond, a woman called Cate, decides to break her out with one of the other kids, a boy called Martin.
Out of Thurmond, Cate reveals to Ruby that she is a part of Children's League-an organization that works on freeing these kids. Ruby soon finds out Cate's and League's ulterior motive which is using the children for their own gains and power.
Ruby escapes and finds herself in the company of three other refugee kids: Liam, Chubs and Zu. They decide to go to East River in search of another remaining orange, a boy that is feared even by PSF's, and going by the nickname of Slip Kid.
The trio eventually finds themselves in a camp of other oranges, but soon discover their dark nature and decide to escape. Then they come upon a father of one of Liam's friends. The guy shoots Chubs and Ruby has no other option but to call upon the Children's League with the device she left in her backpack just in case.
Ruby makes a deal with Cate to be a part of their League in exchange of letting Liam go home. Cate accepts and Ruby wipes the memory of her from Liam's mind. Ruby knows what the League will do to her and in what monster they will try to shape her to be but she is confident that she will also be able to keep her human part.
