In 1936 in Shanghai, Xu Jifa, who was adopted since childhood, was a detective and was ordered to investigate a case of falling from a building. When he was framed and faced with despair, he met his biological mother and brother who had been separated for many years. He learned that his life experience was involved in the gold robbery case 15 years ago. The culprit and the real culprit of the falling case were the same group of people. His brother Lin Yichen was also mistakenly identified as Xu Jifa and killed by them. In order to solve the case and revenge, Xu Jifa disguised himself as his brother and continued to investigate the truth. After going through hardships, Xu Jifa finally brought all the criminals to justice. In the process of investigating the truth, Xu Jifa witnessed the corruption and darkness of the National Government. At the same time, he felt that the tragedy that happened to him was due to the corruption of the entire society. He began to come into contact with new thoughts, from focusing only on personal grievances to caring about the future of the nation. After the outbreak of the Anti-Japanese War, Xu Jifa resolutely embarked on the road of finding light.