In the thirteenth year of the Republic of China (1924), three murders occurred in the Qinhuai River area of Nanjing - antique dealer Fang Heming was strangled to death, private school teacher Sun Wenzao was crushed to death, and Kunqu opera artist Yu Jinqiu drowned. The three cases were classified as "unrelated" and closed hastily, but the mysterious symbol "Si" (snake) was left on the scene.
Ten years later, reporter Shen Jiemei serialized a series of articles called "Old Stories of Qinhuai" in Xinmin Daily in an attempt to expose the truth. However, he was shot dead in Rouge Lane after publishing the seventh article. Before his death, he sent a letter to Lin Mo: "Someone is investigating the incident in the 13th year of the Republic of China."
