Autumn rain continued in Lincheng, and three serial secret room thefts with strange techniques suddenly broke out. Only an Ω rust-colored symbol that was exactly the same as the unsolved case ten years ago was left on the scene, like a lingering curse.
Ten years ago, the detective Su Jianfeng who was in charge of the case accidentally fell from a building as he was getting closer to the truth. The case came to an abrupt end and all the clues were sealed. Ten years later, the symbol reappeared, and his daughter Su Xun was already the backbone of the criminal investigation detachment. Determined to find out the cause of her father's death, she plunged headlong into the mystery of the unsolved case.
Just when the investigation reached a deadlock, Shen Yanyu was officially incorporated into her investigation team by her superiors. He has a gentle temperament but extremely keen observation. He can always accurately capture details that the police ignore: scented candles that are offset by one centimeter, undetectable indentations on the inside of the safe, tampered handwriting in old case files, and traces left at the scene from ten years ago.
He is professional, restrained, cooperative, and never crosses the line, yet he knows the top-secret details of old cases very well. While Su Xun relied on his judgment to advance the case, he was also entangled in the lingering suspicion in his heart - he knew the murderer too well, was too familiar with the scene, and was too clean to have any flaws.
The two of them worked side by side to investigate, review clues, and investigate doubts. They seemed to be cooperating in a tacit understanding, but in fact they had their own thoughts. Su Xun wants to find the truth for his father and uncover the secrets that were covered up in the past; Shen Yanyu stays by her side and uses police authority to get close to the core, but he always hides his own purpose.
As the investigation deepens, the fragments of the old case continue to be pieced together, the outline of the murderer gradually becomes clear, and the fog around Shen Yanyu becomes thicker and thicker. Is he an expert who is here to help solve the case, or is he a man who has been plotting for ten years?
