Xu Mo, a modern young man, accidentally travels back to the seventh year of the Zhenguan era in the Tang Dynasty. He opens a supermarket called the Great Tang Supermarket in Chang'an's Eastern Market. With unusual modern products such as spicy gluten snacks, hot pot, and mahjong, he sparks a series of hilarious interactions with Li Shimin, Cheng Yaojin, and other early Tang officials, princesses, and nobles. Through his carefree, laid-back approach to running a business, he brings an unprecedented wave of novelty to the Tang Dynasty, overturning everyone's understanding of the world.