Coal truck driver Zhou Dayong and his medical student daughter Zhou Xiaoyu, after being maliciously forced down on prices, mistakenly enter an abandoned toll booth and accidentally travel through time to the ancient Yanhui Pass. It is the depth of winter, and the frontier garrison and people lack coal and medicine, suffering greatly from the threats of the Xirong. Relying on modern supplies, medical knowledge, and equipment, the father and daughter travel back and forth between the two worlds time and again, bringing coal, padded winter clothes, medicines, and food, treating severely wounded defending generals, and improving barracks heating. Faced with the invasion of the Xirong large army, they transport drones and infrared security equipment to reinforce the defense line, use cement to repair the city walls, and assist the defending troops in fighting off the enemy with superior tactics against numerical odds. In rescues that cross time and space again and again, the father and daughter forge deep bonds with the frontier soldiers and generals.