Red Rising

Darrow is a Red, the lowest caste in a colour-coded hierarchy, mining beneath the surface of Mars in the belief that he is making it habitable for generations to come. When he learns that Mars was terraformed long ago, and that his people are a slave class kept underground on a lie, he is surgically remade as a Gold and sent to infiltrate the elite that rules him. Pierce Brown's first three novels carry him from a brutal training school for young Golds to open war across the solar system, trading the tight arena of the first book for something closer to a war epic. The saga has continued beyond this trilogy.