Policewoman Tai On-na realizes her latest boyfriend is again not the right guy. She keeps dreaming of SDU Prince Mung Hon-sam coming to her rescue. Some hostage incident takes place at a fast food shop. On-na also happens to get stranded inside. Hon-sam, who is somewhere outside, wants On-na to liaise with him. But On-na’s cowardice alerts the kidnappers. She also accidentally touches some bomb. Hon-sam looks down on On-na as he reckons she is mediocre police officer. But On-na has certain forte. Her years of experience in Records Office coupled with her attention to detail have enabled her to gain thorough understanding of personnel relations at the police station. Hon-sam is urgently requested to assist Superintendent Chan Sam-yuen in foiling some drug deal. Gangster Lau Tat-wah happens to show up to cause havoc. Tat-wah unwittingly helps Sam-yuen catch the drug dealers. On-na runs into Tat-wah at the police station. She somehow feels she knows him.

Hon-sam, Sam-yuen and On-na decide to defuse some time bomb as they cannot wait any longer for EOD people to show up. Hon-sam and On-na are arranged to be protected by staying at some safe house. On-na is thrilled as she realizes she is allowed to “cohabit” with Prince, who she fancies. But Hon-sam just does not like this idea. On-na and her beloved cat move into the safe house. Hon-sam wants On-na to enter into a treaty as Hon-sam is getting more and more annoyed with her. Tat-wah and his mob brother Ng Dan-gei are seeking revenge for Yuen Ying Society boss Ho-nam. They are nearly caught as they go to another gang boss Ching Pak-keung’s sauna place to cause trouble. They then realize they have been taken advantage of as Yuen Ying Society consultant Cheung Yiu-chung reveals the truth. Based on clues provided by Sam-yuen, Hon-sam runs into the bomber at the fast food shop. Naive On-na accidentally angers the bomber.

Hon-sam and Sam-yuen defuse the bomb crisis as they have good rapport. The bomb case is concluded. Sam-yuen encourages On-na to pursue her dream, causing On-na to remind herself of her ambition when she first joined the police force. Tat-wah accidentally accepts an assassination job on Pak-keung. He goes to some old housing estate to reminisce about the old days as he knows he is most probably going to die. He runs into On-na, who has come to explore her roots. Actually, the duo already knew each other many years ago. But they do not recognize each other. To turn down the assassination job, Tat-wah slyly causes himself to be detained at the police station. But his scheme fails, and he then tells On-na some news about Ho-nam’s drug deal. On-na is assigned to a new department as she has solved a case and earned brownie points. But her boss is confrontational Hon-sam!

On-na and Hon-sam are assigned to newly established Cold Case Special Investigation Unit (CCSIU). The duo do not get along. Hon-sam vents this frustration on Chin-chiu as he realizes his team members are lethargic and do not care about their assignments. Some new clues are gathered in a cold case. CCSIU is investigating Mr and Mrs Wan’s missing daughter Ching-ching case. Tat-wah and Dan-gei take shelter in Yiu-chung’s place. They are assigned the task of guarding some remote minibus station. Because of this, they encounter Kin Kwan Cafe’s pretty owner Hui Chin-ying. The duo are certain this is a chance to make career progress as they also find out Yuen Ying Society boss Master Kam is a regular Kin Kwan customer. Hon-sam suspects Mrs Wan has killed her daughter. However, Hon-sam and Sam-yuen have different opinions about whether Ching-ching is still alive. Meanwhile, Mr Wan receives a “letter” from his missing daughter.

Mr Wan is about to break up with Mrs Wan as he is again preoccupied with whether their daughter is still alive. Although Hon-sam and Sam-yuen see this case from different perspectives, but Hon-sam begins to like her. On-na discovers some clue in Ching-ching’s letter to Mr Wan. She coaxes the perpetrator into showing up. The case is solved, inspiring Sam-yuen to realize Ching Fung is always on her mind. She resolutely decides to ditch Hon-sam, who she has just fallen in love with, and go overseas to pick herself up again. CCSIU investigates an indecent assault case and uses team member Fong Siu-kiu as bait to lure the sex maniac into showing up. During the pursuit, Tat-wah flees because he is carrying a gun. But Hon-sam wrongly thinks he is the sex maniac. Tat-wah exactly bumps into On-na.

On-na has lost her gun during her pursuit after the sex maniac. She runs into Tat-wah when she sneakily returns to the incident location to look for it. During their conversation, hopeless On-na mentions why she decided to become a policewoman. Hon-sam just has to vent his frustration on his subordinates. He reprimands On-na for her incompetence. He also scolds other team members. On-na is not giving in. She declares she will catch the sex maniac within seven days. Chin-chiu fetches his mother-in-law Yung Law Mei-lan from work. Mei-lan despises Chin-chiu for being much older than her daughter Yung Chu-dik. Chin-chiu is embarrassed as she also deliberately makes his life difficult. On-na is willing to be used as bait for luring the sex maniac into showing up. Tat-wah offers a helping hand as he empathizes with her. Hon-sam does not believe On-na could restrain the sex maniac by herself. He keeps questioning her about what happened during the arrest.

While Tat-wah is going to meet up with On-na, he runs into Hon-sam, who is tailing On-na. The duo start an argument. Tat-wah raises a glass bottle and points it at Hon-sam. On-na sees what is happening. Hon-sam coaxes team members into going to the countryside to undergo coaching. He scolds team members for lacking team spirit. Hon-sam is disappointed at team members’ performance. Team members keep complaining as Hon-sam then takes the chums to the gym to undergo more training. They form small groups to resist Hon-sam. While team members are undergoing training, they run into Leung Siu-hei and his elite subordinates. They are also provoked into attempting to find out which team is better. Hon-sam and Siu-hei are having a one-on-one fist fight. Team member react coolly after Hon-sam knocks Siu-hei down. Kin Kwan is doused with red paint. Tat-wah and his chums rush to the eatery. The situation is becoming dangerous as they are ambushed by assailants.

Honsam demands CCSIU undergo hellish training.Team members are really suffering.Team members are implicated as Onna avoids target practice.She is willing to accept criticism.Team members are moved as she resorts to completing their tasks all night long by herself.Onna’s colleague Chung Yatdin knows Onna deliberately avoids target practice.The duo team up to pretend they are hurt so that they could be excused.Team members become even more hostile towards Honsam as he inadvertently hurts Onna.Meanwhile, Yiuchung settles issues between the two shops for Chinying as he becomes a shareholder of the eatery.Yiuchung, Tatwah and Dangei have also developed a brotherly relationship.Chinying has a secret crush on Yiuchung.Onna, who is convalescing, remotely instructs team members on how to solve cases.Team members also regard Onna as their leader.They are united in their resistance against Honsam.Honsam is not happy with Onna.Chinchiu persuades Honsam to win team members back by starting withOnna

Hon-sam suddenly goes to On-na’s home to pay On-na a visit. He seemingly wants to sincerely repair his relationship with On-na. On-na supposedly goes along with him. But she gets angry and expels Hon-sam from her home when she turns her head and sees Hon-sam scolding her beloved cat behind her back. Chin-chiu suggests Hon-sam use some maneuver that involves Hon-sam getting drunk in front of On-na, pretending to be pathetic and kneeling down to ask her to resume duty. On-na asks Hon-sam to enter into a treaty. From now on, subordinates are to undergo training according to her methods. She also uses Hon-sam’s drunken clip as a threat. While On-na is investigating a homicide case, she discovers tutorial little brother’s name in the victim’s phonebook. She then tries to dial the number. Hon-sam realizes Chin-chiu is hiding his tracks. He tails Chin-chiu to some old-fashioned building and surprisingly sees Chin-chiu being knocked down by someone, who turns out to be Tat-wah!

Tat-wah gives On-na the cold shoulder. He accuses her of not keeping her promise all those years ago. On-na wants to make it up to him. After much effort, she eventually finds some unique robot which Tat-wah has always wanted. On-na feels hurt as Tat-wah is ungrateful. Pak-keung takes Tat-wah and Dan-gei hostage as he is accused of extortion. Pak-keung wants to sort things out with Yiu-chung. Yiu-chung reveals Pak-keung has been profiting himself. He seizes this chance to take over some bar venue that has been managed by Pak-keung. Vengeful Pak-keung slyly drugs and kidnap Yiu-chung. CCSIU follows up on the homicide case. They sense the story is rather complicated as they discover names of persons who had died in previous two years in the victim’s phone’s contacts list. They also notice some deceased persons have common characteristics. They suspect the perpetrator has some specific aim. On-na is then worried about Tat-wah’s safety.

On-na reveals Tat-wah was a tutorial litter brother. Hon-sam just does not care. He is certain that he is investigating a big case involving some serial killer. He is also competing with Crime Unit. On-na diligently participates in investigation activities as she is worried about the killer targeting orphans. Master Kam chooses to ignore society’s important matters as he insists on repairing Chin-ying’s bicycle, causing Yiu-chung to feel Master Kam is fussing over her. CCSIU finds out the victims were all survivors. Some psychologist tells On-na and Hon-sam a survivor’s behavior become self-destructive due to self-blaming. Hon-sam reckons Tat-wah fits the profile of a self-destructive survivor. Hon-sam deduces that the perpetrator’s killer instinct is aroused as they are jealous of survivors being able to start new lives. He also finds out Tat-wah had beaten victim Wong Kei-on up.

Tat-wah is taken to the police station to give a statement as he has become a homicide suspect. On-na suspects Hon-sam has prejudice against Tat-wah. Hon-sam counter-accuses her of unreasonably defending Tat-wah. The duo keep arguing. On-na is worried about Tat-wah. She feels guilty about not keeping her promise all those years ago. To prove Tat-wah’s innocence, she promises Tat-wah she will conduct a thorough investigation. Siu-hei is clueless about this case. He then tries to find out Hon-sam’s investigation progress. He also tells his people to track Hon-sam and his chums. After much investigative effort, Hon-sam and On-na eventually identify the perpetrator. They rush to the perpetrator’s home and realize Siu-hei and his team are one step ahead. However, certain signs in the back stairwell cause On-na to deduce that the perpetrator is probably going to do something bad to Tat-wah. The perpetrator attacks Tat-wah. Tat-wah gets into a dangerous situation as he protects Chin-ying.

Tat-wah feels bothered as On-na keeps asking him about everything. Master Kam assigns Tat-wah and Dan-gei to Pak-keung’s unit. Pak-keung seizes this chance to play a prank on the duo by telling them to take care of some drunken lady called Miss Miu Miu. Tat-wah suffers all kinds of insults in silence. To keep On-na away from Tat-wah, Hon-sam asks team members to work overtime together, causing the chums to feel fed up. Team members are plotting to flee without On-na. On-na is caught when she is sneaking away. Her escape methods just do not work. Dan-gei passes out after ingesting “poison coffee”. Meanwhile, Siu-hei takes this team to some bar to inspect licenses. To safeguard Pak-keung’s bar, Tat-wah takes “poison coffee” with him and flees as he wants to distract Siu-hei. Dan-gei is chucked into some back alley. He is unconscious and vomits white foam.

Tat-wah surprisingly manages to avoid being caught by Siu-kei and deliver the drugs to Pak-keung, causing Pak-keung to see him in a new light. Master Kam have doubts about Pak-keung’s competence. Master Kam covertly urges Yiu-ching to keep a close watch on Pak-keung. Hon-sam tells On-na to keep informing him of investigation progress. He also deliberately clings to her. On-na runs into Hon-sam at some supermarket. She is shocked to realize he regularly talks to his deaf servant Mrs Kwong. She realizes Hon-sam is actually a friendless loner. Chin-ying finds out Yiu-chung has lost his treasured lighter, so she buys the same model for him. She then realizes Yiu-chung has retrieved that particular lighter, which was a memento left behind by his late father. To express his gratitude to Chin-ying, Yiu-ching invites Chin-ying to see a movie. Chin-ying undergoes a meticulous makeover and meets up with Yiu-ching. Tat-wah gets jealous as he sees what is happening.

Siu-kiu accidentally locks herself up in interview room. Team members then realize she has been covertly spending nights at the police station, causing the chums to harshly criticize her. Siu-kiu is embarrassed. Pak-keung is unhappy about Yiu-chung gaining more influence. He uses boxing practice as an excuse for deliberately beating Tat-wah up in front of Yiu-chung. Yiu-ching feels he just has to intervene. But Tat-wah counter-accuses Yiu-chung of snatching Chin-ying. The duo abruptly start a fight. On-na is bothered by Hon-sam all day long. She scolds Hon-sam for using work as an excuse for forcing her to keep him company because he is lonely. Hon-sam pretends to be pathetic and wins On-na’s sympathy. Hon-sam is depressed as he spends “divorce anniversary” by himself. Worried On-na reaches the scene. She escorts drunken Hon-sam back to his home. She also keeps him company.

After spending a night together, On-na and Hon-sam are questioned by Chu-dik, Chin-chiu and their chums respectively. They deny that they have affectionate feelings for each other. Pak-keung’s minion nearly finds out Tat-wah actually knows On-na quite well. Hon-sam lures On-na away by again pretending to be lonely. But On-na catches him out. On-na eventually finds out Tat-wah is a decoy. Tat-wah puts up a front that he is coordinating with Pak-keung. But he is covertly collaborating with Yiu-chung as he wants to use elderly gangsters’ influence to remove Pak-keung. On-na keeps confronting Hon-sam as she wants to show off her fighting spirit to Hon-sam. She launches an investigation into an old case of robbery of jewelry shop. But she is attacked when she questions Yat-din. Yat-din is in danger. On-na fails to open fire as she cannot overcome certain psychological barriers. The situation is dangerous.

A clip showing Yat-din bravely catching robbers goes viral. Netizens are lapping it up. His son even regards him as a hero. Conversely, On-na’s inability to open fire has become a mockery. She is embarrassed as some old clip showing her awkward firing posture is retrieved. On-na is thinking of quitting. On-na eventually picks herself up and opens fire as Hon-sam encourages her to start target practice again. Hon-sam also seizes this chance to tell her what is on his mind. On-na is going out with Hon-sam. But the couple have to keep their relationship secret because team members do not like Hon-sam. Tat-wah eventually has a chance to go with Pak-keung to participate in some drug dealing event. He covertly liaises with Chin-chiu as he wants to round up Pak-keung and seize his goods. But Pak-keung catches Tat-wah out and even points a gun at him.

Tat-wah manages to use delaying tactics to let Siu-hei and his team foil the drug deal. Yuen Ying elderly members scold Pak-keung for jeopardizing the society due to his own business interests. But Pak-keung scapegoats his minion Bobby. Master Kam makes an example of Tat-wah by deliberately hitting him as he knows Pak-keung has committed a blunder. He also reassigns Pak-keung’s operations to other elderly members except Yiu-chung. The sauna place is inexplicably inspected. Tat-wah senses Yiu-chung is ruthless as he finds out Yiu-chung just wants to play games. Chin-chiu suspects Hon-sam is going out with someone. He then asks On-na to find out who is Hon-sam’s girlfriend. He also tells her to make them end their relationship. On-na and Hon-sam find something in the lonely death case, and On-na’s girlfriend Koo Yee-ling is surprisingly implicated.

On-na and Chu-dik ignore Yee-ling as they are so angry with Yee-ling as she has not told them she is married. Meanwhile, On-na also ends her friendship with Chu-dik as she is afraid of Chu-dik realizing she is going out with Hon-sam. Yee-ling rents a luxury apartment as she is pretending to live the high life. She lies to her buddies that this love nest purchase has been financed by her husband’s family. But her lie is exposed. Ah-fat angrily brings up the topic of divorce as he senses Yee-ling despises him for running an unprofitable theatrical company. Chin-ying feels lost as Yiu-chung abruptly goes cold on her. Yee-ling obtains something left behind by her late father. She is shocked to find out some secret about her background. Siu-kiu’s mother Fong Chan Choi-fung, who is a dementia patient and also care home resident, is missing. Siu-kiu finds her and then takes her to the police station. Choi-fung keeps shouting at Siu-kiu, who just has to tolerate her mother.

On-na comes clean with her girlfriends about going out with Hon-sam. However, she catches sight of Hon-sam’s ex-wife Kwan Sha-doi, who even kisses Hon-sam. On behalf of On-na, On-na’s girlfriends question Hon-sam about his relationship with Sha-doi. They urge On-na to be vigilant. Sha-doi goes to CCSIU to look for Hon-sam. Her irresistible charm mesmerizes team members. Sha-doi specifically asks Hon-sam to help her boss Chin Shun-chiu find some missing cat. She also reveals she knows Hon-sam is going out with On-na. On-na goes to see Shun-chiu because of the missing cat. She realizes Shun-chiu actually does not care about the missing cat. Tat-wah tracks down the boss who is bankrolling Pak-keung’s drug deals. He covertly tells Chin-chiu to swing into action. Soon after, Siu-hei leads his team to round up the drug dealers. Pak-keung launches an attack by opening fire. Siu-hei aims his gun at Tat-wah.

Yiu-chung saves Tat-wah, who hazily recalls an old family extermination case. While On-na is looking for Shun-chiu’s missing cat, she becomes suspicious as she catches sight of Shun-chiu’s chauffeur. She then finds out the chauffeur had definitely taken Shun-chiu’s cat away. But the cat is dead. On-na returns the cat’s ashes to Shun-chiu, who startlingly smashes the urn. Sha-doi and Hon-sam have tacit understanding. On-na feels uneasy as she seems like an outsider. Some morning walkers discover Yiu-chung’s father’s remains among which Tat-wah’s father’s watch is also found. CCSIU launches an investigation into Tat-wah’s family extermination case that took place twenty years ago. They suspect there is still something to be uncovered in this fatal robbery. While Yiu-chung is looking for Chin-ying, Pak-keung comes to seek revenge. The duo are in a dangerous situation.

CCSIU reaches the conclusion that Yiu-chung’s father Cheung Shing was the perpetrator behind Tat-wah’s family extermination. Hon-sam’s questioning of Master Kam causes Yiu-chung to become suspicious of Master Kam. Yiu-chung and Chin-ying become a couple as Yiu-chung tells Chin-ying he loves her, causing Master Kam to scold Yiu-chung. But Yiu-chung keeps confronting Master Kam. He even points out his father’s death probably had something to do with him. To compete with Sha-doi for attention, On-na adopts a lady boss look and returns to the police station. But Hon-sam laughs at her. On-na is annoyed and ignores him. Hon-sam uses some claw doll to win On-na back. Sha-doi is surprised as Hon-sam has no self-respect because of On-na. Sha-doi tells on On-na to Shun-chiu when she finds out On-na’s new cat looks the same as Shun-chiu’s missing cat. In the evening, someone sneaks into On-na’s home and even assaults On-na.

On-na’s injury is not serious. But her newly adopted cat is missing. Sha-doi happens to catch sight of that cat at Shun-chiu’s home. Hon-sam and his ex-wife’s wedding anniversary is coming up. On-na lines up some activities for accompanying Hon-sam as she is worried about Hon-sam feeling sad, just like the way he felt about his divorce anniversary. But she realizes Hon-sam completely forgets this date. Tat-wah undergoes hypnosis and recalls even more childhood memories. He recognizes one of the perpetrators behind the family extermination is Yiu-chung’s father Cheung Shing. Tat-wah is agitated. He finds Yiu-chung and sorts things out with him. He even reveals the other perpetrator was a man with a snake tattoo on his hand. Master Kam covertly orders Pak-keung to deal with Yiu-chung. Meanwhile, Yiu-chung unexpectedly catches Master Kam.

Vengeful Yiu-chung argues with Master Kam over his father’s death. Master Kam recalls grudges between him and Cheung Shing. He points out Cheung Shing first sent some people to kill his family. He ended up losing his beloved wife. He asked someone to look after his daughter Chin-ying. Yiu-chung is not happy about Master Kam boasting that he is his foster parent. Yiu-chung is furious as Master Kam brought him into Yuen Ying but did not let him manage business operations. Hypnosis causes Tat-wah to recall certain memories. He sees the perpetrator behind the family extermination in his dream. Hon-sam’s big auntie returns to Hong Kong. “Meeting the parents” makes On-na nervous. However, on the day of meal gathering, On-na is late because of the cat search. Sha-doi ends up meeting big auntie first. The duo readily get along. On Sha-doi’s advice, On-na offers some chocolate gift to big auntie. But Onna has offended her. Shadoi tells Onna she is doing everything she can to snatch Honsam back.

Sha-doi seizes some chance to move somewhere closer to Hon-sam. On-na is at her wits’ end as she is overwhelmed by Sha-doi’s shenanigans. Tat-wah is not happy with Yiu-chung currying favor with Shun-chiu. Yiu-chung comes clean about using Shun-chiu for drug deals. He emphasizes that he is going to team up with Tat-wah to seek revenge on Shun-chiu after his status in Yuen Ying is consolidated. Kai-fan is annoyed as Hon-sam and On-na refuse to investigate Tat-wah and Dan-gei. He even wants to be reassigned to Siu-hei’s Crime Unit. On-na feels defenseless as Sha-doi acts like she is the boss at Hon-sam’s home. On Chu-dik and Yee-ling’s advice, On-na tells Hon-sam she wants to cohabit with him. But her beloved cat cannot adapt to the surroundings. Hon-sam comes up with some plan as he knows On-na is feeling anxious. Chin-ying accidentally overhears the truth about Master Kam getting into trouble. The situation instantly becomes dangerous.