Huo Jin received an anonymous letter: 'You owe me your life, you will be clean tonight'. The unsolved case from seven years ago was rekindled, and the deceased had the same 'V' carved on his neck as his teammate back then. His former partner Shen Zhao appeared in a dark alley and dropped key clues, but refused to explain why he was alive. Forensic doctor Bai Lu is keeping an eye on Huo Jin's every move, female reporter Su Rui is filming in the dark, and the gentlest deputy director in the bureau is stitching up the blood debt of that year with his own hands. Tonight, truth and blood die together.
Huo Jin followed the clues of the 'V' copper coin and tracked down Lao Di in the scrapyard in the east of the city. Before he died, the latter left a sentence: 'A gray bird flies seven times, but a man lives once.' At the same time, Shen Zhao planted forged instructions in the police station's database, inducing Chen Xiao to misjudge that Huo Jin had all the evidence, forcing him to activate the 'clearance agreement'. In order to confirm that Huo Jin was the murderer, Bailu arbitrarily retrieved the surveillance video, but found that the video of brother Su Rui's death completely overlapped with the mission time back then - she was the only outsider who knew about it back then. Shen Zhao's true identity is exposed. He is not a betrayer, but a shadow undercover who took the initiative to die for Huo Jin. All the clues are traps he weaved with his life, just for Huo Jin to expose Chen Xiao with his own hands. When Huo Jin ran into Chen Xiao in the secret room of the police station and was about to blow up the archives, he discovered that the 'V' on the copper coin was actually the first letter of 'Vengeance'. Tonight, it was not him who wanted to save his life, but the whole city who wanted to clear his name. Su Rui sent the video to the entire Internet, Bailu chose to destroy all the reports he had tampered with, and Shen Zhao's body had been cremated three hours ago - no one knew that he had carved the last key into Huo Jin's bone marrow.
