During a self-driving trip, four childhood friends accidentally travel back to the seventh year of Xuanhe in the Northern Song Dynasty—1125 AD, with less than two years remaining until the Jingkang Incident. A veteran history blogger, a restaurant owner, and a high school chemistry teacher—four modern people with no money, no household registration, and no background—can only find a way to survive in the Great Song. But when they know that the Jin army is about to march south and Bianjing will eventually fall, a question lies before the four of them: since they know the historical outcome in advance, can they change the humiliation of Jingkang?