The story is set in Republican Shanghai. Four young people with completely different experiences in life come together to break into the underground world of “Qianmen Jianghu” and solve mysterious cases. Su Zi Quan (Ning Huan Yu) is quick-witted and calls himself the “number one master sleuth on earth”. Despite his excellent memory, he can’t recall his early childhood. His biggest weakness, however, is that he’s allergic to women. Whenever he comes into physical contact with a woman, he has to sneeze. Tang Dai Yun (Shirley Jin) is a pure and kind-hearted, but also willful rich young lady. While looking for her lost older brother, she meets Zi Quan. Joining these two is the cold butler of the Tang household Chen Yi Ming (Li Dai Kun) who has great fighting skills and is only gentle to Dai Yun, and Zi Quan’s childhood friend Lu Zi Xiao (Zhu Ya), the only woman he’s not allergic to.
Legend says that once in thousands of years, the door to the Realm of Gods opens and the child of the King of Hell is born on earth. Evernight follows and the peaceful earth is thrown into turmoil. In the 15th year of the Tang dynasty, woodcutter Ning Que (Chen Fei Yu) takes his maid Sang Sang (Song Yi Ren) with him and enters the capital. He manages to pass the exam for the most reputable academy and becomes the discipline of the academy’s leader. When Sang Sang suddenly suffers from a mysterious disease, Ning Que finds out that she’s related to the evernight. In the blink of an eye, Sang Sang becomes the target of all humans. Ning Que and Sang Sang then start roaming the world in order to protect Sang Sang.
Doctor Ji Xian Yun (Yang An Qi) is reborn as a princess in ancient times, but has retained her knowledge from the modern world. She relies on her medical knowledge to survive. When she meets the pregnant prince Qi Ling Xiao (Cheng Ying Hao), a sweet and funny love story ensues.
The drama follows an ordinary scholar named Yang Ling (Jiang Jin Fu) on his way to become a royal highness of the Ming dynasty. On his wedding day, Yan Ling suddenly falls down and can’t get up anymore. While recovering from his illness, he looks at his new wife Han You Niang (Crystal Yuan) and realizes that he feels ashamed of being poor. He thus decides to sell his field and goes to take the imperial exam. When Yan Ling helps uncovering a murder mystery, he gains recognition from the county magistrate who lets him work as teacher, which allows Yang Ling to prove his worth. On the battlefield, he meets the crown prince Zhu Hou Zhao (Liu Rui Lin) who went undercover and they become partners and friends. Yang Ling will fight alongside Hou Zhao against conspiracies and eventually help him ascend the throne.
Li Mi (Jackson Yi) is the head of Chang’an’s anti-terror department, and is tasked with investigating a group of mysterious Turks who have infiltrated the city. Zhang Xiao Jing (Lei Jia Yin) is a former imperial army officer turned constable who is currently in prison after breaking the law, though is set free because Li Mi believes he is the only person who can solve the mystery. Zhang Xiao Jing’s familiarity with the city’s alleyways and the habits of the Turks leads him to the conclusion that their ultimate goal is to create havoc during the Lantern Festival. Wth less than a day left before the event, the two must race against time to protect the capital and its people.
The Legend of Hao Lan depicts the fights between the Qin and the Zhao state towards the end of the Warring States period. After Zhao’s imperial censor Li He gets caught in a trap and goes bankrupt, his daughter Li Hao Lan (Wu Jin Yan) is sold to Lü Bu Wei (Nie Yuan). Bu Wei will later offer her to the King of Qin Sun Yi Ren (Mao Zi Jun) who is held hostage in Zhao’s palace. Bu Wei and Hao Lan enter the palace where they have to outwit Princess Ya (Hai Ling) and others who try to harm them.
When working in the desert, archeologist Yun Ye (Wang Tian Chen) suddenly gets transported back to the Tang dynasty. There he meets Li An Lan (Zhang Jia Ning) who looks exactly like his former girlfriend. He repeatedly uses skills learned in the modern world to save An Lan and surrounding people from danger. People start to appreciate him and he even becomes best friends with the crown prince. But then he gets drawn into a huge conspiracy.
The Emperor of Qi and crown prince Xiao Ding Quan (Luo Jin)’s enemies aren’t few. When the emperor kills Official Lu Ying, he puts the blame on Ding Quan as his death helps Ding Quan pave the way to the throne. In order to avenge her father, Lu Wen Xi (Li Yi Tong) enters the palace under the pseudonym “Ah Bao”. But while testing Ding Quan again and again, she slowly develops feelings for him.
In the early years of the Republic, Bai Lu Sheng (Yang Hao Ming)’s entire family is murdered, only he is lucky enough to escape. An old friend of his father takes him in and he grows up together with his cold and ruthless son Long Xiang (Zhao Cheng Yu). Long Xiang’s dream is to become president, but Lu Sheng who made it his life mission to avenge his family gets in his way.
The second season continues the story of general Tang Qing Feng (Zheng Ye Cheng) and Flower Star’s soldier Ah Bu Cha Cha (An Yue Xi) as they encounter new adventures. The love between the alien and human couple disrupts the order of space and time. In order to save it, Tang Qing Feng is arrested and they go back to the Tang dynasty to find the truth. However, an accident occurs and they land in the Sui dynasty where they encounter Qing Feng’s ancestors.