Ping invites Ko and Fung over for dinner. Fung mentions Ho's past. It infuriates Kong and he returns to his room where he reviews newspaper clippings about Ho. Kong cannot forgive Ho, who let Nam get away and also because Ho died in the bed of a prostitute. Shan accidentally discovers severed human limbs. Kong presumes Nam must be out killing again, and vows to arrest him. Kong discovers Ho's old mobile phone. It suddenly connects to Ho's mobile phone number from 20 years ago, starting a father-and-son conversation in different time-spaces.

Twenty years ago, Ho promised to look after Nam's father, Kow. However, he suspected that Nam had been in touch with Kow throughout that time. So he called Fung and accidentally got in touch with Kong. Shan meets Chiu through the internet and they start discussing the case of the severed limbs. With Ho's help, Kong manages to track down Kow's whereabouts. On his way to find Kow, Kong runs into Shan and her younger brother Ming. They find that Kow is having an asthma attack. Meanwhile, Shan reports her whereabouts to her publisher and is surprised to see Lam at the hospital. She probes Lam and concludes that he is, in fact, Nam.

Kong proves that Nam is not the murderer. Shan then asks Kong to pretend to be her boyfriend to camouflage herself with the image of an unfaithful lover so as to lure the lovelorn murderer into light. The murderer tries to harm Shan, but she manages to escape. Kong and Shan discuss a sentence the murderer has used from Nam's university thesis. Kong asks Ho to go to the university and track down the person who has stolen the thesis. But Ho falls asleep. Luckily, there are clues on the security camera tapes.

Wealthy businessman Shing commissions Shan to write a biography of his late wife Ling. Shan goes to pick up love letters written by Ling when Shing receives a blackmail letter for $10 million or else Ling's past as a prostitute would be disclosed. Kong is in charge of the case. Shing receives blackmail photos of Ling with a customer. Ping discovers that the customer is Ho.

Shing decides not to get the police involved. Kong tells off Ho for having been caught in pictures with a prostitute. Ho pretended to be a customer in order to arrest a brothel owner. Ting plans to follow Shing on his way to pay the blackmail money, but fails. Kong finds the blackmailer, who says that Ling committed suicide after she was blackmailed. He also says that Ho used to see Ling a lot. Shan finds Ling's suicide note in her greenhouse.

After reading Ling's suicide note, Kong realises that Ho was genuinely trying to help Ling with her problems - hence Kong has wrongly accused Ho. He wants to call Ho, but finds it difficult to tell Ho that Ho will not be alive in 20 years' time. Kong and Ping review Ho's case and find his cause of death suspicious. Bill suddenly wakes up from his 20-year coma, but has lost part of his memory. Kong is assigned the case and attempts to find out who pushed Bill off a building 20 years ago.

Lan feels uneasy after reading about Bill's recovery in the newspaper. Shan discovers that Lan's real name is Fan, and suspects that she has something to do with Bill's case. Bill blackmails Lan. Shan is shocked to learn that she is the illegitimate daughter of Bill and Lan.

Lan tells Shan about her past with Bill. He often tried to harm Lan. To protect the baby, Lan - by accident - pushed Bill off a building. She denies that the baby was Shan. Kong discovers that Ching is the illegitimate daughter, not Shan. Lan wants to settle things with Bill, but he accidentally falls from a hotel window. Kong identifies Lan as a murderer. Ching is flabbergasted to learn that she is Lan's illegitimate daughter. Shan blames Kong for mistaking Lan as a murderer and is gravely disappointed with him.

Shan wants to invite Kong to an auction of a famous diamond called the Star of Cupid. It is said that those destined to be together will see at the same time the same image reflected on the diamond. However, Shan is too shy to ask. Wealthy widow Madam Ching receives a blackmail letter, and asks the police to step up security measures at the auction.

Shan runs into Kong at the auction. Simultaneously, they both see the image of the legendary Cupid. Shan is pleased, but decides to give way to Ching when she learns that Ching is attracted to Kong. The Star of Cupid is stolen. Kong claims that from the security cameras, he sees someone sneaking into the auction. But Ting is unable to find evidence to support what Kong has described. Kong is suspended from duties for internal investigations. Kong feels low, but Shan is there to comfort him.

Ho is shocked to learn from his check-up that he has cancer. Ching courts Kong but he subtly rejects her. Kong is delighted to see text messages on Shan's mobile phone and reveals his own fondness for her. However, Shan would rather give way to Ching and dismisses Kong's feelings as one-sided.

Ho is relieved when he discovers that his medical report was swapped with somebody else's and thus he does not have cancer. Ping is attacked, but Ko risks his life and takes a stabbing intended for her. Kong manages to clear his name and resume his duties.

Ching eventually accepts Ko's love. They then try their best to match Kong and Shan, who are both fond of each other, and finally succeed. When Shan and Kong go out on dates, they are laughed at because Shan is confined to a wheelchair. She feels ashamed and worries that she might become a burden to Kong.

Shan feels that she is not good enough for Kong and suggests breaking up with him. Kong digs out newspaper clippings from 20 years ago about Shan's car accident. He decides to change her destiny. Following Kong's instructions, Ho manages to save Shan from her childhood tragedy. Kong then goes to Lan's home to look for Shan but is shocked to find that Shan has been missing since she was seven. Moreover, Ching has now become Kong's girlfriend. Even the outcomes of the previously solved cases involving Shan have changed. Kong never expected that history would be rewritten because Shan was saved. Triad leader Sun is murdered and Kong sees Shan in a related videotape.

Kong saves Shan again from an attack, but she loses her memory. Kong takes her to see Lan, who immediately identifies Shan as her missing daughter. Kong finds someone to hypnotise Shan to restore her memory, but the attempt is in vain. Shan is attacked again and suddenly remembers her home and identity. It turns out that after being saved by Ho, Shan lost her way until she met Sun, who adopted her and named her Wan. Sun sent Wan to Canada to study as he did not want her to get involved in triads. After thorough investigations, Kong suspects that Sun was murdered by his mistress.

Kong finds out that triad leader Sun was a homosexual and his partner was Yu, his henchman. He suspects that Yu murdered Sun. Kong brings up some past events with Shan, but she has no recollection at all.

Kong refuses to give up and asks Shan to be hypnotised for one last time, but to no avail. She wants to go back to Canada, but he persuades her to stay with Lan.

Ho learns that Shan is not Sun's adopted daughter. Shan befriends Ching but talks about her behind her back to win Kong's sympathy. Ho tells Kong his suspicions about Shan, and Kong senses that she has some dark secrets.

Shan's adopted father turns out to be Kun, Sun's henchman. He uses Shan so he can gain control of the gang. Meanwhile, someone tries to kill Shan and Kong suffers a serious stab wound protecting her.

Shan is moved and confesses her feelings for Kong. Kong persuades her to leave the underworld and offers to give up everything to start a new life with her overseas. To turn Kong and Shan against each other, Kun makes Shan think that Kong has been using her only to solve the case.

As Shan confronts Kong, a gunshot is heard. Shan thinks Kong fired the shot and vice versa. Ho finds out that Shan was kidnapped by Kun when she was young and lost her memory in an accident. Shan thought Kun had saved her life after she regained consciousness. Kong is worried that Kun might kill Shan and rushes to her rescue. Kun reveals his true character and Shan decides to take Kong's side.