Terror at the Opera House

During the performance of the musical "Sunset Boulevard", Li Mingxuan, the son of a wealthy man, was shot and killed in the opera house, and the sound of gunfire on the stage served as a perfect cover. The investigation uncovered the culprit scandal in a car accident three years ago, and even led to a murder case 20 years ago. Everyone involved has secrets and revenge plans. Who is the real murderer?