In the republican era of Changsha, nine powerful families known as the "Mystic Nine Clan" protect the town. Zhang Qishan (William Chan), the leader of the nine gates, investigates a mysterious train arriving at his station, which leads to an enigmatic mine. He enlists Qi Tiezui (Ying Haoming) and Er Yuehong (Lay Zhang), an opera singer from an archaeological family, to solve the mystery. Before their mission begins, they must first find medicine to help Er Yuehong's terminally ill wife. During their journey, they encounter Yin Xinyue (Zhao Liying), the young hotel mistress, and uncover a dangerous plot threatening Changsha's people. This is a 2016 South Korean prequel to "The Lost Tomb" that explores the intricate world of historical mystery and adventure.