Jiang Xiangdong time-travels back to 1978, becoming a temporary worker at a supply and marketing cooperative. Facing material shortages and a rigid system, he uses modern thinking to optimize allocation and gets to know the mysterious stone spirit Lai Cai. Together, they cooperate to clear supply chains and resolve villagers' urgent difficulties. Starting from half a catty of brown sugar, Jiang Xiangdong gradually builds an efficient commercial network, achieving a win-win of personal value and social contribution in the tide of the era.