Criminal policeman Liu Hongtao is a master at solving cases. His colleagues reversed his name and nicknamed him "Detective Red Six of Hearts", but this unexpectedly got Liu Hongtao into trouble. Recently, a red six poker card was found at several crime scenes. In order to find out the truth, Liu Hongtao followed the clues and found Ma Yan, the contact person of the criminal gang. Unexpectedly, Ma Yan died suddenly, and the clues were interrupted. Liu Hongtao fell into layers of mystery from then on. After hard work, Liu Hongtao found the murderer who killed Ma Yan, but unexpectedly, this person turned out to be Li Xiaojun, the boyfriend of his deceased comrade's sister. In the face of evidence from Liu Hongtao's multi-party investigation, Li Xiaojun confessed that a behind-the-scenes mastermind code-named "Red Six of Hearts" had been secretly helping him hide the facts of the crime. In order to catch "Red Six of Hearts", Liu Hongtao, under the careful arrangement of his superiors, made Li Xiaojun an informant. Just when Liu Hongtao locked the suspect, he was framed as the hidden "Red Six of Hearts". Liu Hongtao used the trick to make the criminal "Red Six of Hearts" mistakenly believe that the trick had succeeded. Liu Hongtao eventually captured the real "Six of Hearts", uncovered a criminal gang that colluded with corrupt officials, and cleared himself of suspicion.