On the eve of the fall of Peiping in 1937, Qi Mogeng, an apprentice at the bookstore, and Cheng Xueqing, a lady from the Chengji bookstore, pledged their love with "Mogu" copper coins. They hid anti-Japanese intelligence with the piano score of "Youlancao" and condensed their mission of protecting Liulichang's cultural heritage into a ledger. Cheng Xueqing was kidnapped to protect the account, and Qi Mogeng jumped into the sea with the account. The account book was sealed for a hundred years with indigo dye and tung oil. When the National Edition Library opened in 2024, Cheng Xueqing's granddaughter Cheng Xingye woke up the ledger at night, causing Qi Mogeng to wake up across time and space. AR recreates troubled times, DNA matches kinship, and copper coins unlock secrets. The two finally solve a century-old mystery at "Mo Gu Chu" and use the ledger as a matchmaker to complete a "reconciliation" agreement that spans the century, allowing the cultural context of Peking and the deep love of troubled times to last forever.
