Cold chain driver Zhao Dayong and his medical student daughter Zhao Xiaoyu, while delivering goods, encounter a runaway merchant and accidentally enter a misty tunnel, time-traveling to ancient Yanhui Pass. Relying on a truckload of fresh vegetables and bottled water, the father and daughter use modern supplies to solve the border pass's water and vegetable shortage crisis, and use medical knowledge to cure the tetanus of old border-guard general Pei Jun. Traveling back and forth between modern times and ancient times, they procure medicine, water exploration equipment to drill water wells, and also bring seeds and drip irrigation technology to improve border agriculture. When Xirong's Helian Lie launches a massive invasion, the father and daughter travel back again, transporting modern security equipment such as drones, infrared detectors, walkie-talkies, and protective gear to help Pei Zhao's garrison build a technological defense line.