Ten years ago, Interpol Lin Jianguo fell from a building and died. The official conclusion was that it was "suicide". His daughter Lin Wan did not believe it, but was unable to change anything and could only leave a permanent scar on the palm of her hand. Ten years later, she was the youngest trace appraiser in Jiangcheng and did not believe anyone until Interpol Captain Shen Lu came to the door with a bullet casing that had been deliberately aged. He said that he had been investigating for three years, only because of his father's last words before his death, "I did something wrong." Two people who were trapped by their parents' secrets joined forces to track down a cultural relic smuggling network from a bullet casing, and uncovered the secrets of two generations of criminal police from an old file. When the truth was revealed layer by layer, Lin Wan found that she was not only facing a murderer hiding in the dark, but also a betrayal from the person she trusted the most, and Shen Lu's father was one of the insiders back then. This is not a simple story about chasing a murderer, but about the boundaries of obsession, trust and betrayal between two generations - ten years of tracking, the truth is as heavy as a mountain, but this time, she is no longer alone.
