The world suddenly restarts and resets to zero, and Lin Ye, an overweight, useless homebody, is the only one cast into the primitive Old Stone Age. Stranded among a primitive tribe, he is despised by everyone. Using modern common sense and survival knowledge, he makes straw sandals to earn their acceptance, overcomes fierce opposition to quell a plague, and exposes a neighboring tribe's shaman and his poisoning plot. He then smelts copper and casts tools, clears land for farming, and builds towers to fight drought, using his ingenuity to overcome successive crises of war and famine. Shedding his cowardice, Lin Ye wins the tribe's respect through his sense of responsibility, marries Xi He, and rises to become the tribe's leader. Yet strange lights appear on the horizon, hinting that unknown dangers still lurk behind the world's restart.