Joe grandpa four's identity was discovered by that person in the second episode, because the case in the second episode was the disappearance of a textile worker, involving Joe grandpa four's boss Bai. In the process of solving the case, Lu Yao knew the true identity of Grandpa Joe.

Detective of the Republic of China mainly tells the story of high flyers who returned from studying in Shanghai during the Republic of China. The inspector of the patrol room and a female reporter jointly solved a bizarre murder case.