Inspector HUI WAI-SUM of the Witness Protection Unit(WPU) and his squad have accomplished the task of protecting a key witness in a drug trafficking trial, which is highly praised by his superior LAU CHAM-KWAN. WAI-SUM goes home to rest, while his fellow colleagues - CHAN KAR-SHI, YEUNG YIU-TUNG, CHEUNG LAI-KUEN and others seize the opportunity for cakes and ale. Later on, WAI-SUM pays a visit to his aunt CHAN YUK-LAN in her fruit store, and she invites him over for dinner. However he is so exhausted that he oversleeps. Upon arrival, he realizes that YUK-LAN and her family have postponed their dinner time just for him. Just then, his cousin, LI HAU-YAN, coaxes him into buying her a tablet computer. Offhand he agrees. Tycoon KIU KONG-HO hangs out with chums for a drink. Out of the blue, a hidden shooter fires upon him, creating a furor among the city……

Quite the opposite, CHI-LAM shows her father a delighted smile upon their returning to her room. For fear CHI-LAM will be disturbed, KONG-SHAN forbids WAI-SUM and his squad from going up to the second floor, which leaves KAR-SHI and YIU-TUNG an unfavorable impression. YIU-TUNG goes to a dinner with WAI-SUM at YUK-LAM’s home, during which he is dazzled by HAU-YAN's trendy style. WAI-SUM bumps into a group of construction workers on his way home, triggering a flashback to his childhood. Although he was rescued from a fire by his neighbor - a construction worker, he lost his parents in that fire. Having found out that KONG-HO is in fact targeted by HUNG FEI, a really powerful man in Shenyang, KONG-SHAN asks a favor from an intermediary – Director CHOU to negotiate with HUNG FEI. CHUN-KAI proposes to KONG-HO that he is planning to run a casino with pals in Malaysia, yet is blown off……

Assistant Commissioner of Police Bao Sir meets up with KONG-SHAN at KIU's home, during which he implies that the police have surmised his secret reconciliation with HUNG FEI. Though smiling, KONG-SHAN utters not a word. HUNG FEI comes to Hong Kong to meet KONG-SHAN, and have a pleasant chat with the KIU brothers. KONG-HO gets stinky drunk so that HUNG FEI offers to give him a lift. However he speaks out of turn infuriating HUNG FEI. All of a sudden, HUNG FEI pulls out a pistol and fires on him. By accident, a foreigner is shot to death by a stray bullet. The whole scene has been caught up by CHI-LAM. HUNG FEI is taken under custody by Patrol Sub Unit (PSU). KONG SHAN dashes for the hospital to visit his brother knowing that a disaster is imminent, as it turns out that the victim is actually a retired judge. HUNG FEI's driver pleads guilty, which differs from CHI-LAM's testimony……

During ID Parade, CHI-LAM bursts out screaming and flees from the room as soon as she sees HUNG FEI. SIU-LEUNG reports to KONG-SHAN, indicating that HUNG YEE has sent his henchmen to wreak havoc on his subsidiary companies in Shanghai and Chongqing. Misconstruing that CHI-LAM is in trouble, WAI-SUM breaks into her room, which scares her to death. Boiling with rage, KONG-SHAN gives WAI-SUM a severe telling-off. WAI-SUM is called back to the police station by CHAM-KWAN the next day. It turns out that KONG-SHAN offers to disclose CHI-LAM's secrets to him. A fire breaks out when CHI-LAM is practicing in the Sinfonietta. After escorting her from the fire scene, WAI-SUM nonetheless rushes back to the blaze retrieving her cello in the nick of time. In fact, some assassins sneak into the fire scene. Assuming that he has got rid of them, WAI-SUM, however, runs into another group of assassins……

Outpouring the agony of anxiety in a morning storm with gusty winds, CHI-LAM plays the cello so loud that annoys MEI-HUNG, who is feeling unwell. In the eyes of KA-SI, LAI-KUEN and others, this has crossed the line. KONG-HO reveals to WAI-SUM the cause of CHI-LAM's illness in hopes of clearing up the misunderstanding. Endeavoring to prove his worthiness to KONG-SHAN, CHUN-KAI boldly follows a gangster YUEN-KWAN back to the mainland to negotiate with HUNG YEE, but ends up being seized and maltreated. SIU-LEUNG goes to his rescue. Noticing that HUNG YEE is captured, HUNG YUNG, the youngest of HUNG brothers, has to disguise his anger cooperating with KONG-SHAN. YIU-TUNG promises to buy HAU-YAN a new telescope as gift trying to win her affections. CHI-LAM drops in at her former residence in Shek O, where she gets help from WAI-SUM in setting up an astronomical telescope for stargazing at night……

A theft has reportedly taken place in the house and sixty thousand dollars in cash has vanished. MEI-HUNG points the finger at WAI-SUM's teammates, but she is requested not to pursue it further by KONG-SHAN in hopes of burying the hatchets. Nevertheless, WAI-SUM is resolved to look into the matter on his own. With CHI-LAM's assistance, he manages to prove that the members of WPU are in the clear. To show his gratitude for her, he gives her a cactus as gift. Having learnt from the Manager of the Sinfonietta that the world-class pianist Hack Martin would like to collaborate with them for exchange performances, CHI-LAM is thrilled and eager to give a try. That meets with fierce opposition from WAI-SUM, but he finally gives in and assents to her request. CHI-LAM returns to her former residence for rehearsal, during which her favorite scarf blows away……

Not wanting to have too many strangers at the performance, KONG-SHAN reserves tickets exclusively for those from his commercial circles, leaving limited seats for the public. As the show drawing to an end, CHI-LAM receives flowers from a foreign musician in blonde, soon afterwards, she gets attacked. Upon discovering that the attack is initiated by HUNG brothers, KONG-SHAN is consumed with rage. In order to seek revenge, he has SIU-LEUNG recruit international assassins against them. On the other hand, under WAI-SUM's influence, CHI-LAM finally pulls herself together and her mood starts lift, as those around her are aware.

In the detention center, the news of his brothers' consequence exasperates HUNG FEI so much that he throws a chair towards the TV set. Escorted by WAI-SUM, CHI-LAM finally arrives at the court. At first, she answers the questions raised by the prosecutor without any hitch. Her mood starts to slip away when the defendant lawyer deliberately points out her mood disorders. Faced with few rounds of questioning, she inclines towards depression and even her father can not soothe her. Only WAI-SUM's encouragement sees her through. As things are settled, a celebration is held for CHI-LAM with great enthusiasm. However CHI-LAM appears reluctant to be apart from WAI-SUM following KONG-SHAN's announcement of the withdrawal of the WPU. To cheer her up, KONG-SHAN specially brings her to an amusement park where she encounters HAU-YAN. They take a picture together and HAU-YAN takes the initiative in leaving her contact information.

KONG-SHAN invites the members of WPU to dine out and plans to return home with his daughter afterwards. Unexpectedly, CHI-LAM suggests going to karaoke with them. She later reveals to Kelly that she is having a crush on WAI-SUM, however, Kelly believes that is just the transference of her feeling instead of true love. CHAM-KWAN notifies WAI-SUM of his promotion and transfers him to the Crime Unit. Knowing that YIU-TUNG is wooing HAU-YAN, WAI-SUM comes to realize that he is decoyed into her love trap. He tries to persuade YIU-TUNG to let go of her, but he is so blindly in love and goes ahead notwithstanding. Trying to win KONG-SHAN's support, CHUN-KAI starts pursuing CHI-LAM and eagerly expects his date. But much to his disappointment, KONG-SHAN and KONG-HO show up for the appointment. What is more, KONG-SHAN assents to his proposal of investing in casino provided that he gives up on her.

WAI-SUM, CHI-LAM, YIU-TUNG and HAU-YAN go hiking together. Unlike HAU-YAN, who keeps grumbling about weariness, CHI-LAM instead quite enjoys herself being accompanied by WAI-SUM. Sensing that CHI-LAM has an affection for WAI-SUM, HAU-YAN not only volunteers as her dating adviser, moreover, she shares the photos that WAI-SUM and CHI-LAM have taken together on a social networking website for her reviewing. Her model friend leaks the website password to the journalists to attract media coverage, resulting in the exposure of the pair's photos. Discovering this, KONG-SHAN is completely infuriated. Thinking that it is WAI-SUM who keeps pestering CHI-LAM, he declares that WAI-SUM does not deserve his daughter and in no way he could be her Mr Right. Under SIU-LEUNG's pressure, HAU-YAN deletes all the pair's photos. Feeling that KONG-SHAN has taken it amiss, she requests to have a word with him……

In an attempt to make up for the pair, HAU-YAN goes to talk to KONG-SHAN, who flies into a rage slapping her right away, which astonishes WAI-SUM to no end. Hastening back home, CHI-LAM unreservedly admits to KONG-SHAN her love for WAI-SUM, who promptly turns her down, leaving KONG-SHAN no time to digest it. After reserving the tickets of an orchestral concert , CHI-LAM sends a text message invitation to WAI-SUM, who agrees to go. In fact, he just takes the chance to imply that he sees no future with her. Overwhelmed with sorrow, CHI-LAM finally accepts the reality then leaves. Having the mindset that WAI-SUM is still pestering his daughter, KONG-SHAN determines to teach him a lesson. Following his sudden complaint to POON Sir and CHAM-KWAN, WAI-SUM is confronted with the allegation about taking advantage of his position to pursue private matters……

While thinking the chances are slim after her audition for a part in movie, HAU-YAN gets the role eventually with KONG-HO's help. In a vain attempt to blank out WAI-SUM by keeping herself busy, CHI-LAM heads out alone to SAI KUNG for an excursion in the hope of recapturing that joyful moment with him. Learning this from MEI-HUNG, KONG-SHAN thinks that she is merely taking the opportunity to meet with WAI-SUM. CHI-LAM wanders around the countryside without knowing that she has entered into the rugged mountain path. For fear of severe thunderstorms erupting soon, KONG-SHAN tries to reach CHI-LAM by phone. Failing to get an answer, he urges KONG-HO to call BAO Sir for help in search of her. Having known CHI-LAM is missing, WAI-SUM is resolved to find her whereabouts so he goes to Sai Kung in person. Finally reaching the point without any communication signal, surprisingly, he finds CHI-LAM lying unconscious on the hill slope.

Upon returning from Malaysia, CHUN-KAI conveys good news to KONG-SHAN, which is that SAPURA, an Indonesian business magnate, is seeking a joint venture partner in Hong Kong for expansion of container terminals. As soon as he hears the name, KONG-SHAN appears pale all over. Later on the four richest people - KONG-SHAN, SHUI-BONG, PAK-KEI and YIU-TO are invited by CHUN-KAI to attend a banquet hosted by SAPURA, who appears as though they have never met before, which again greatly puzzles KONG-SHAN. By chance, WAI-SUM becomes aware of the traffic collision that YIU-TUNG gets involved. He then goes to question HAU-YAN on a hunch that she is having something to do with this. CHI-LAM writes to WAI-SUM relaying that she is heading to Germany for treatment of her injured hands. When returning to the Crime Unit, WAI-SUM runs into MRS LAM who holds a confession letter pleading to reverse the verdict for her son……

To seek proof of a relationship between SAPURA and KONG-SHAN, WAI-SUM meets up with KONG-SHAN in China Prosperous Xing International Co. (CPX). During the meeting, KONG-SHAN asks WAI-SUM to make a choice between CHI-LAM and his police career. For whichever choice, WAI-SUM is entangled in a dilemma. While he treasures his relationship with CHI-LAM, he has no intention to sacrifice his dream job. Having learnt from SHUI-BONG that SAPURA is so anxious to get the deal done, KONG-SHAN cannot help getting suspicious. He gets even more upset when drunken CHUN-KAI shows up in the middle of KIU brothers' conversation mentioning his father's tragic death thirty years ago. CHI-LAM's recovery from the hand injury is proceeding well so she decides to return to Hong Kong early. Moreover, having gone through inevitable challenges, she has also completely recovered from her mood disorder……

Knowing that the U.S. Securities and Exchange Commission (SEC) is investigating SAPURA's company, SHUI-BONG, PAK-KEI and YIU-TO decide to suspend the investment schedule, which turns SAPURA's plans topsy-turvy. With him threatening to raise the past event, KONG-SHAN has no choice but to inject a total of $20 billion cash into SAPURA's company. Reflecting on the past that has been buried for thirty-three years, KONG-SHAN feels compelled to make a decision...... Ever since CHI-LAM returned from Germany, she has been keeping track of WAI-SUM through text messages without knowing he is agonizing about whether to choose a career over love or vice versa. Besides straightforwardly urging CHUN-KAI to leave Hong Kong and start anew in Malaysia, KONG-SHAN explicitly informs WAI-SUM to relinquish his struggle of choice-making……

CHI-LAM comes back home shedding no tears for the break-up, making KONG-SHAN worry about her emotional status. Meeting up with HAU-YAN the following day, she is reassured that there has been no involvement of a third party. Exhaling a sigh of relief, she makes a promise to herself secretly. Launching an investigation into a smuggling case, WAI-SUM and his squad make geological reconnaissance of remote islands here and there. While thinking all done, KONG-SHAN receives an unanticipated call from SAPURA, who picks a fight with KIU brothers over bygones shortly after they meet, inflicting grievous bodily harm on both sides. To get him medical care, SIU-LEUNG, together with KONG-HO, takes KONG-SHAN to a back-alley "doctor". Having settled them down, SIU-LEUNG then sets sail on a yacht in search of SAPURA.

Landing on a remote island early in the morning, WAI-SUM leads his teammates scouting around for clues. Simultaneously, SIU-LEUNG traces severely injured SAPURA to an abandoned house, where he comes across YIU-TUNG, who is on a mission. Ahead of their encounter, YIU-TUNG has learnt from SAPURA about the buried past. Desperate to keep KIU brothers' secret, SIU-LEUNG abruptly strikes at YIU-TUNG. In addition, having analyzed the current situation upon reporting to KIU brothers, he plans to sacrifice himself if necessary. Taking into account that KONG-SHAN's late wife was SAPURA's old flame, POON Sir specifically urges each team member to keep an eye on KONG-SHAN. Following the death of SAPURA, KONG-SHAN is summoned to help the police with their inquiries, during which he successfully counters all the questions raised by WAI-SUM……

As there has been no breakthrough in the case of SAPURA, under WAI-SUM's suggestion, members of two Units have a meeting together, successfully yielding fresh clues. Later on when KONG-SHAN and KONG-HO return to the illegally-run clinic for further consultation, they get caught by WAI-SUM and his teammates right in the act. Besides investigating on the evidence retrieved from SIU-LEUNG's home, WAI-SUM has computer experts recover the deleted data from his computer, leading to core evidence to solve the case. He then goes to arrest KIU brothers, which is caught up by CHI-LAM, who is left standing stock still in great fear. At a critical turning point, KONG-SHAN manages to evade the responsibility and get away with the alleged crime. Arriving at home safe and sound, he instantly slanders WAI-SUM by accusing him of entrapment in front of his daughter, however he fails to make a very convincing point……

Concluding that his action of firing a gun across border has severely violated the ordinance, WAI-SUM is finally dismissed. While being reluctant to part, his teammates promise to continue the investigation on his behalf. Coming across CHI-LAM right at his front door, WAI-SUM insists that KONG-SHAN is the mastermind of the alleged conspiracy to murder SAPURA. Thinking of the tremendous discrepancy between two of her beloved persons, CHI-LAM is nearly heartbroken. Feeling so desperately helpless, she turns to Kelly. On the heels of a heart-to-heart conversation, she opts to leave Hong Kong for academic studies abroad. CHUN-KAI moves back to Hong Kong seeking KONG-SHAN's aid after he lost his business in Malaysia. However, KONG-SHAN is steadfast on his stand refusing to pay off his debts anymore……

Ever since FUADI's return to Indonesia, WAI-SUM has lost contact with him, who according to CHUN-KAI is caught in the middle of the legal battle over his late father's estate against his father's mistress. It turns out that SAPURA was not Chinese Indonesian. Inspired by CHUN-KAI, WAI-SUM reorganizes all the bits and pieces. SHUI-BONG and PAK-KEI calls on KONG-SHAN relaying that he is elected as chairman of the Chamber of Commerce. Sarcastically, KONG-SHAN has no idea how to react to it. As CHI-LAM's departure is around the corner, WAI-SUM invites her out to ease the tension of the slip-of-the-tongue by tendering his apology followed by a present as compensation. For verification, KONG-SHAN goes to ask CHI-LAM, who not only confirms it but also reveals her injury inflicted at that time, which scares KONG-SHAN out of his wits. He then calls up his brother telling him to flee away as soon as possible……