The Imperial Secret Agent Long Long Jiu (Nick Cheung) was asked by the "Sword Saint" Ye Gucheng (Andy Lau) to arrange a duel with the "Sword God" Ximen Chuixue (Ekin Cheng) on September 15th at the Hall of Supreme Harmony in the Forbidden Palace to determine who is the best swordsman in the world. The duel between the "Sword God" and the "Sword Saint" immediately shocked the martial arts world. People in the martial arts world used it as gambling money, and gambling was rampant. In order to avoid trouble, the court sent Long Long Jiu and the imperial sister Jin Yanzi (Vicki Zhao) to jointly prevent the duel. Jin Yanzi has always admired Ye Gucheng and forgot her purpose during the action. Long Long Jiu found out that a mysterious force was planning a big conspiracy and was waiting for the opportunity on September 15th.