The mysterious and unsolved “Snowman” murder case rattles the city, with the killer taunting the police with notes saying “Come to catch me” at the crime scenes. With a last hope of breaking the case, the chief calls back the dismissed and rogue detective, Yan Liang. While the local public defender, Guo Yu, has a chance reencounter with his high school love, Zhu Huiru, as she gets embroiled in a homicide case.
Detective Yan discovers some interesting details about “The Snowman” case while scrutinizing one of the crime scenes. He finds out about a local hoodlum that goes by the name of Blondie, who says he caught a glimpse of the killer.
Without knowing anything about the underworld, local lawyer Yu pays Blondie to act as a mediator for Huiru in negotiating with the gangsters. Come the night of the planned meeting and “negotiation”, Yu and Huiru accidentally kill Blondie in a struggle for their lives.
Yu and Huiru unravel after the killing of Blondie. A mysterious man appears to help them clean the crime scene, erasing all the evidence of them being there. When Blondie's body is found by the police, Yu and Huiru automatically become suspects because they were the last people seen with him. Without any concrete proof, the police have to let them go.
Without any new evidence or suspects, Detective Yan has no choice but to start over from the beginning. Luo Wen, a former forensic medical examiner, and Yan's ex-partner, enters the picture.
A series of murders for a missing journal puts the city on edge. The infamous The Snowman killer reappears, and complicates matters for everyone. Murder suspects Zhu Huiru and Guo Yu navigate a world they don't understand.
Detective Yan makes a bold move. With a surprise encounter between Yu and Huiru and Detective Yan that turns into an impromptu interrogation, Yu breaks down. He confesses everything under the extreme pressure of the questioning. Another murder case is reported. Local gangster Zhang Bing is killed by “The Snowman”.
Cold-blooded thug Li Fengtian collects debts for local gangsters. Murder suspect Yu's boss, Mr.Jin, owes a lot of money to some very bad people. In trying to save himself, Mr.Jin attempts to blackmail his young protégé.
Detective Yan gets some unfortunate news about his ex-partner, Wen. Yan comes up with an elicit ruse to trap Wen in one of his lies. It works. Wen confesses to everything, but refuses to provide any evidence.
While Yu finds a way to escape being blackmailed by his boss, he soon realizes that he has become the target of the underworld fixer, Li Fengtian.
Li Fengtian catches up to Yu.
His ex-partner Wen, who was in police custody, escapes and is now on the run.
Detective Yan comes close to completing the puzzle that is “The Snowman” investigation.
The truth becomes clear for the first time.
Alongside the series of murders shaking the city, the search for the journal continues. Survival has Zhu Huiru facing betrayal from those she trusted, as the real killers responsible are revealed. As the end nears, an unlikely partnership helps to make sense of why “The Snowman” killer reappeared.
After two long years, Detective Yan is still working the case, as it becomes clear Huiru is his last real hope.
As Huiru and Yu finally clear their names, and they can finally get married, conflicts and suspicions still remain between them. Huiru chooses to believe Detective Yan as she is desperate for the truth about her brother's death. While Yu hires Li Fengtian to kill Detective Yan.
Huiru tricks Yu into telling her the truth about her brother's death. Fengtian suddenly reappears, to erase any last links tying him to the recent string of murders.