During the Wanli period of the Ming Dynasty, Japanese pirates teamed up with spies in the court to frame the entire family of Minister of War Qiu. Only his youngest daughter, Qiu Moyan, was rescued by the chivalrous Zhou Huaian. Before his death, Qiu handed over the Ming Dynasty's coastal defense map to his daughter, hoping that when the court was in peace, he could entrust this map, which was related to the safety of the Ming Dynasty, to someone who could take on the responsibility. In order to obtain the defense map, the Japanese pirates hunted Zhou Huaian and Qiu Moyan on the rivers and lakes, and the court also listed them as the number one wanted criminals. For the safety of the defense map and the descendants of the Qiu family, Zhou Huaian turned to Jin Xiangyu, the proprietress of Longmen Inn, for help. For the sake of her beloved, Jin Xiangyu hid the defense map in the inn, and turned the inn into a dragon boat hidden outside the rivers and lakes to protect the defense map until the right time comes. Unexpectedly, Qiu Moyan accidentally fell into the hands of the Japanese pirates. At the same time, the court also sent Xu Yi, a master of solving cases, to the boat to capture Zhou Huaian and Qiu Moyan. Several forces fought desperately on this strange dragon boat for their own purposes.