Red Rising by Pierce Brown

Red Rising is the first book in a science fiction trilogy that takes place in a dystopian future where society is divided into color-coded classes. Darrow, the protagonist, is part of the Red class, the lowest and most oppressed workers living underground on Mars. They believe they are terraforming the planet for future human generations, but Darrow discovers that Mars has already been habitable for centuries and that the ruling Gold class controls everything. Motivated by loss and anger, Darrow infiltrates the elite Gold class with the aim of toppling their brutal regime from within.