Traveling through time to the primitive society of ten thousand years ago, crossing over into a member of a small tribe named Ren, yet bound to the sacrificial altar due to extinguishing the sacred fire. In a desperate situation, relying on making fire by drilling wood to defy the heavens and change fate, not only escaping the sacrifice, but also making the tribesmen witness for the first time that fire is a miracle created by humans. Yet wanting to survive is not easy, as the tribe faces a crisis of winter annexation. He is forced to use modern knowledge to upgrade primitive civilization, making fish baskets, improving weapons, planning survival strategies, and using a sports student's physical strength and a worker's brain to lead the tribesmen in a counterattack in the prehistoric world where the strong prey upon the weak.