Modern-day criminal investigation expert Xia Ren accidentally travels back in time to the ancient Ming Dynasty, inhabiting the body of a county magistrate. By coincidence, he arrives in the middle of a courtroom trial. After accessing the original owner's memories, Xia Ren realizes that the case may be a false accusation. Using modern investigative knowledge, he successfully clears the victim's name. However, this also earns him the enmity of a wealthy local merchant's son. Soon afterward, the emperor personally orders Xia Ren to investigate a horrific family massacre that has left the local population terrified.