In "Red Rising" by Pierce Brown, the main conflict revolves around the protagonist, Darrow, who is a member of the lowest class in a highly stratified society. He becomes part of a rebellion against the ruling elite known as the Golds. The conflict is primarily centered around Darrow's struggle to infiltrate the Golds and bring about justice and equality for his people, known as the Reds. It's an intense and action-packed story filled with political intrigue, battles, and personal challenges.