On the eve of his execution, Cheng Ye, a former criminal policeman who was despised by the entire Internet, found a subcontracted button in his cell - it belonged to the deceased in the first serial murder case, but it appeared at a scene he had never been to. Forensic doctor Shen Zhao secretly passed on the DNA code of the real murderer, prison guard Bai Xiao handed over key recordings, and reporter Su Ling revealed the overlap of old cases ten years ago. When the chain of evidence points to the top brass of the police station, Cheng Ye and Shen Zhao must detonate public opinion in the city within 72 hours, and his apprentice Chen Yan is holding a copy of the evidence that can destroy them.
