Everything in life can be measured, and everything in life is measured. Each person who has ever lived has five Numbers on their arm, defining the five primary attributes of that person. Throughout someone's life, these will increase with time and effort, and all of society revolves around these Numbers. What happens when this natural system of Numbers, the basis of all of society for all of history...changes?

Atlas and his friends have made it through the first few weeks of the inclusion, surviving monster attacks, strange aliens, and psychopathic humans. And now, with their Numbers and knowledge increasing from each encounter, they're stronger than ever. But the monsters around them are getting stronger too, racing for the power that comes from growing Numbers and gaining skills. As they make their way home...can Atlas and his friends keep up?