In the prison, SHEK TUNG SING recalls his memory of getting commendation and preparing for promotion examination in the police force… Fifteen years ago, SING was dissatisfied that a rapist was acquitted on all charges with the help of his defense lawyer and the victim eventually committed suicide. The lawyer and his wife were being attacked at home. SING was there coincidentally and he fainted after a hit at the back. When SING woke up, he was shocked that both the lawyer and his wife were killed by his gun. The most critical witness of the case was SING’s best partner MAI ON DING. SING’s wife KAN CHUK KWAN was pregnant when he was sentenced to jail and they separated from each other for 15 years since then. Editor of Bao Magazine, HUI MAN HIM, makes the lawyer’s case a feature story and this helps to reverse the verdict of SING’s case unexpectedly……

SING goes to visit the dead lawyer’s secretary Ms AU and he discovers that some important information were not recorded in the case’s file… DING learns that CHONG SHUN has scolded SING and he consoles SING. However, SING didn’t reveal to DING that he has collected some new evidence. SHEK LONG dates her mother KWAN but KWAN finds JIT there with present and flowers… Somebody reports to the police that smelly water is coming down from the upper floor. SING arrives at the scene and he breaks into the suspicious flat. He discovers Uncle MAO sitting on the kitchen’s floor and a dead woman is found under the stove. The neighbours say that the dead woman WAI MEI came from mainland China and she married Uncle MAO for half year only. Later, Uncle MAO locks himself in the flat and commits suicide…

SING, DING and SZ carry out investigation in Uncle MAO’s home for they believe that Uncle MAO was killed by somebody… After discussion, they believe that MEI’s cousin is the key suspect and SING suggests luring him with MEI’s missing cat. MEI HA informs KWAN that KA CHAI is missing. KWAN is very nervous and she asks JIT to help finding him. SING returns home and he meets JIT… SHUN asks DING to clear the misunderstanding between him and the magazine editor. DING invites HIM for lunch but they start a quarrel again… SZ pretends to be the shopkeeper of a pet shop. HING FAI comes to adopt MEI’s cat and SZ talks with him. SING risks his life to capture FAI and DING rescues SING recklessly…

Uncle MAO’s case is resolved. SING brings all colleagues to JIT’s pub for celebration. SHUN introduces the retired superintendent KO LAP YAN’s son KO KEI YEUNG, probationary inspector, to everybody. He tells them that YEUNG will be working with them soon. Before the deadline, HIM is wondering if she should publish the headline story. While having late dinner with SZ, SIU KEI informs HIM that their boss Mrs BAO has decided to print HIM’s headline story without getting her consent… Some mysterious internal organs are found in the countryside and the police carry out investigation. DING seizes the chance to play tricks on YEUNG. They continue the investigation in nearby village and Village Head HO worries if the organs belong to his missing son… A blood-stained altar is found in the countryside… A child is missing and the police discover another blood-stained altar in the countryside…

The team learns that CHUNG, father of a missing child, has returned to Hong Kong so they visit him. Scavenger CHUNG reveals to DING that he was quarrelling with his wife TSZ KUEN since they were unable to pay their son’s school fees and his son was missing after that… HIM visits CHUNG with reporter TAI BUN. After sending CHUNG food and subsidies, HIM leaves CHUNG her name card and asks him to call her anytime. After some careful analysis, SING believes that CHUNG is a dangerous person but he doesn’t have enough evidence to search his place. SZ has an idea suddenly. HIM and TAI BUN visit CHUNG again to bring him an electric fan. While BUN is setting up the fan, HIM put a mini-camcorder at the window… SING tries to pick KWAN up at work but he discovers that JIT is trying to hold KWAN’s hand by force on the street…

The case of CHUNG is over and SING takes leave to go traveling with his wife and daughter. After visiting various places in Sabah, SING decorates the hotel room nicely. However, KWAN suffers from allergic rhinitis and she falls asleep quickly after taking medicine… SHUN asks SING to see him for he learns from YEUNG that SING was violating the rules when investigating CHUNG’s case. YEUNG apologizes to SING and DING about this. He also tells to them that a past drug trafficking case might be related to SING’s case. Reminded by YEUNG, SING remembers that he met a drug trafficker called SHING in the jail and SHING told him that he was innocently accused of taking 5 million dollars of trafficking money on his own. DING asks an old friend to investigate if the victim FUNG was involved with money laundering. SING learns that the police officer who worked on his case has found the FUNG’s secretary’s statement eventually…

SHUN reveals to SING that he had made a wrong decision long time ago after receiving huge pressure from his ex-boss LAP YAN. SHUN believes that the one who stole the drug trafficking money was KIM WAI and he asks him out… SING follows WAI secretly and discovers that he is meeting YAN… DING meets SING after work. SING tells him that he has already made an appointment with a retired social welfare officer to find out who had adopted FUNG’s daughter. KWAN calls SING to tell him that she is suffering from abdominal pain. Since SING is busy at work, KWAN says that she will handle it by herself. However, she cannot bear the pain eventually and she calls JIT. SING and all family members rush to the hospital and KWAN tells them that she is fine. SING finds JIT making a phone call at the hospital’s snack bar. JIT is saying that his friend is suffering from pancreatic cancer……

SING goes to pick LONG up at her school. SING reveals that he has decided to divorce KWAN… DING asks HIM to write an article about a festival at the walled village. He hopes that this could attract the emigrated neighbours of FUNG, Mr and Mrs BA, to return to Hong Kong so that he could check the whereabouts of FUNG’s daughter SIU YAU from them… DING joins the festival at the walled village and he pretends to be the nephew of an old neighbour of Mr and Mrs BA. He finally gets the information he wanted. SING wants to tell SZ the truth but HIM stops him. While HIM and SING argue with each other, SZ and YEUNG overhear their conversation accidentally. LI returns home with a heavy basket. SZ suddenly appears to ask questions about her childhood…

SHUN and everybody go to the ward but SZ has disappeared. SING and DING invite HIM to meet up at the pub. They tell her the whereabouts of SZ… The Serious Crime Unit learns that some mainland robbers have came to Hong Kong to commit crime. SING allocates the job duties of everybody. SHUN suddenly arrives to ask the whereabouts of DING… HIM accompanies SZ to receive hypnosis therapy from DING. However, the therapy is terminated because SZ has recalled some terrible scenes from the past… The police capture all the mainland robbers. SING continues investigation in nearby areas and he discovers a suspicious man called SAU TAI FU. HIM helps to follow YAN. She finds that he is meeting FU so she takes picture of them secretly. She then follows FU but FU stuns her. DING tries to rescue her and they are trapped in a freezer truck…

DING, SING and YEUNG believe that FU may harm SZ. They decide to protect SZ privately and YEUNG takes the initiative to be bodyguard. YEUNG stays in SZ’s living room. After midnight, YEUNG hears an explosion at the swimming pool and he rushes out with his gun. FU sneaks into the house and he tries to kill SZ… SING and everybody report the case to SHUN. During the meeting, the superintendent Mr LAW suddenly arrives… DING and SING discover new evidence at the place where FU attacked SZ but they try not to let YEUNG knows… FU follows YAN. He overhears YAN’s conversation with WAI and he realizes that YAN will not give him what he wants. WAI is killed by his own gun. The Serious Crime Unit comes to carry out investigation and they find that someone has written threats in red paint on the ceiling…

DING and SING asks YAN out privately but YAN reveals that he cannot help them… YAN returns home to find that YEUNG has read the threatening letter from FU. YAN drives to the countryside to hand over the money to FU. FU comes to take the money but the bag suddenly explodes… DING and SING arrive to find that YAN is injured by gunshot. SING discovers FU and he starts a gunfight with him. DING follows the sound of the gunfire. He discovers that SING has collapsed and FU is killed by gunshot… BI FU, team leader of Serious Crime Unit B, discusses the case with DING and SING. He wonders who has hurt SING and killed FU… YEUNG visits SZ and learns that she wants to transfer to another unit. YEUNG also reveals that he has decided to resign…

DING discusses SZ’s application for transfer with SING during lunch. He reveals that he has held her application in order to help YEUNG. During the time, BI FU arrives to reveal that the third person who killed FU may not exist… Informed by SING, SZ arrives at a crime location to find a naked dead woman with make-up. There are roses around her and the scene looks both mysterious and romantic… HIM suddenly appears to take pictures for she has followed SZ to the location. HIM’s ex-boyfriend WAI KIN visits her at the office and he asks her to continue paying the rent for he has moved out from the flat already. In order to get back the memory card from KIN, HIM asks DING to assist her. The Serious Crime Unit finds the assistant photographer RAY suspicious. They follow him and discover that RAY is…

After raping the model YUKI, the rapist decides to kill her but he is frightened away by the alarm of a police car. At the hospital, SING finds her daughter arrives breathlessly and he realizes that YUKI is LONG’s senior schoolmate… DING carries out investigation at the countryside and he tries to figure out the normal practice of the killer… YEUNG suggests luring the killer and SZ voluntarily requests to be the bait… SZ goes to the photo studio and asks FRANKY to take pictures for her again. She tries to get close to FRANKY and she asks YEUNG’s team to keep a longer distance from her when she leaves the studio… YEUNG finds that SZ is missing. He tries to follow the suspect’s car but his car crashes with a suspicious truck unexpectedly… HIM goes to FRANKY’s studio to pick up the photo and she is attacked by a mysterious man at the back staircases after leaving the studio…

SING carries out investigation at FRANKY’s studio and he finds a USB memory stick… FRANKY is released and he provokes HIM deliberately… DING goes to visit HIM for he wants to send her chocolates but he discovers that HIM is sending SING present… ON NA’s father commits suicide at her grave. ON NA’s mother reveals that he was deeply tormented after watching the video from the killer. The video shows how ON NA was raped and killed. FRANKY’s truck is caught in a car accident. SING seizes the chance to search through the truck and he finds something suspicious. The crime is over and SING is highly praised by the victims and their family members. He is promoted to Station Sergeant. SING’s attitude is changed after this…

KWAN starts working as an accountant in the publishing company. SING wants to date her on her first working day but KWAN already dated JIT… After DING prepares his cup noodle, HIM suddenly arrives angrily. On the next day, DING reminds SING to treat HIM nicely. HIM’s colleague KA KUEN is fired and HIM asks DING to drive her to KA KUEN’s place. KA KUEN is drunk and he is biting his wife HO MEI HUNG… DING learns that somebody has collapsed at an alley and he discovers that this person is HUNG. SING questions KA KUEN and KA KUEN reveals that he loves his wife very much. HUNG suffers from breast cancer and KA KUEN works really hard to raise money for her. He eventually suffers from kidney disease because of overwork. YEUNG follows KA KUEN and finds him attacking his neighbours Mr and Mrs LEUNG because he believes that they had killed his wife…

DING and SHIM LEUNG go to KA KUEN’s home at night. They ask why KA KUEN tries to shift the guilt to his neighbours. After admitting his sin, KA KUEN collapses. The doctor says that he is suffering from acute kidney failure… HOI CHING suddenly sends present to YEUNG and dates him out for dinner. SZ discovers that YEUNG returns the present to CHING and he reiterates that they are colleagues only. HIM invites KWAN to shopping and she wants KWAN to help selecting SING’s birthday gift. KWAN celebrates with SING one day before his birthday and she suggests him to date HIM on his birthday… SING spends a romantic evening with HIM but he reveals that he still misses KWAN… DING drinks alone at home and HIM suddenly arrives to drink with him. They are drunk and make love with each other…

DING and SING go to the hospital with KA KUEN’s father. The doctor says that a kidney is suddenly available for organ transplantation… In order to please HIM, DING searches for her vanity table everywhere. While cleaning the table, DING discovers the photos that HIM has been keeping… LI LI invites DING to dinner at home but HIM suddenly says that she wants to take over the flat. SZ scolds HIM for acting against DING all the time. She later realizes what had happened between them and she leaves angrily… The truck driver PETER is caught in a traffic accident after drinking alcohol. This causes the death of the groom CHEUNG CHI HIN’s wife and family members. However, the judge releases PETER eventually. Later, PETER is killed in a car accident. YEUNG and the others carry out investigation at HIN’s place and they discover that HIN’s car was used by others…

SING observes the car burning ceremony of a mysterious group of people. He then follows HIN’s grandmother’s car. Later, a man gets out from her car at a scrap yard. DAVID LAW, car owner of the burnt car, was sued for causing the death of others by driving carelessly. After checking out the video, the team believes that the host of the car burning ceremony is the most suspicious person. SZ recognizes that this person is the ex-racer LUI KIN. Some hikers discover a burnt truck and the police confirm that this truck belongs to PETER. The team therefore believes that the car burning ceremony is a prelude of a murder… LO HANG and LEUNG rush to protect DAVID LAW but he is killed in a car accident already… LEUNG and CHING go to the scrap yard to carry out investigation on LUI KIN but LUI KIN says that he was with YIN LING, volunteer of the Traffic Accident Counseling Center, during the time…

During the team meeting, SING reveals that he discovers a sculpture at LING’s home that looks like the mace that LUI KIN uses during the car burning ceremony. HANG recognizes that this sculpture is LUI WO (one of the creatures of the world in Chinese myths). DING and SING go to visit the prison to visit ROBERT who killed LING’s son in a car accident… The team follows LING and LUI KIN. They find that LING is giving a bag to LUI KIN. LING then gets rid of YEUNG and his team. SING and his team discover that LUI KIN is leaving Hong Kong… LING meets her mother while visiting her son’s grave. She has been away from home ever since her son died. YEUNG and SING carry out investigation at LING’s home and they discover a notebook behind the sculpture. YEUNG asks SING to keep the notebook but SING loses it. LEUNG discover that the notebook has been thrown to a brazier… YEUNG tries to arrest LING at her old home but…

SING drinks alone at the pub and KWAN comes to console him. LONG suddenly arrives to inform KWAN that JIT has been promoted and she would like to celebrate with him. The police discover that somebody is selling drugs in JIT’s pub and the boss fires JIT. DING asks HIM out to declare his love to her… A cleaner discovers a hand and the police are not able to identify the person for the hand is boiled… The Serious Crime Unit learns from a restaurant staff that three young men, KAM SAI MAN, TO LIK KEI and CHAN HUNG NIN, are hiding in an abandoned old building. It is confirmed that the ring belongs to WONG WING CHI. SING follows NIN and discovers that CHI has not died… In order to find the head of the killed woman KITTY, SING provokes CHI with ghost story…

The team arrests the three men who wanted to kill CHI but the three men deny that they are murderers. The team thus bring the three men to the crime location and DING reveals his inference to them… HIM reveals to her family members that KIN wants to have the money back by selling the flat. DING learns about the case and he decides to accompany HIM to meet KIN. SING discovers that somebody has robbed the prostitute SUK KUEN’s money. He helps SUK KUEN and they become friends. DING and HIM return home hand in hand. They reveal to LI LI and the others that they are dating. SING discovers that JIT is trying to open a pub. He deliberately threatens the illegal alcohol seller and makes him selling his products cheaply. In order to save money, JIT really buys alcohol from the illegal seller and he is arrested by the customs officers…

SING rushes to SUK KUEN’s place after receiving her call but she is already died when he arrives. SING and CHING carry out investigation at the doctor TING YUEN HO’s clinic. Afterwards, SING asks CHING to make a medical appointment with another dead person’s name and they discover that this dead person is also the patient of HO. SING and CHING follow HO. They discover that HO visits a prostitute directly after work. Later, SING learns that another prostitute is died. The prostitute’s neighbours say that the murderer is a woman who wears hat. SING visits HO and discovers that he is injured. HO reveals that it was TRACY who hurt him. HIM brings the reporter to the beach where a female ghost has been haunting and they discover NANCY in red dress…

DING and LO HANG visit HO to inform him that they have arrested a woman who looks like TRACY. HO goes to look for girls in the pub at night and he meets SZ who dresses sexily for she wants to seduce him. The Serious Crime Unit follows HO and SZ’s taxi. They find a woman with hat driving after them. DING asks the team to continue following them and he goes to another place. The mysterious woman is arrested but she is not holding a surgery knife… DING rushes to the building and he says that the murderer is not TRACY. YEUNG loses contact with SZ and he breaks into the flat. After a fight, the murderer runs away and YEUNG is seriously injured…

LEUNG is safeguarding the offender at the hospital and SING visits him with food during his holidays. After chatting with LEUNG on the phone, DING finds something strange and he rushes to the hospital but the offender has died… DING is suffering from serious headache for his brain tumor is getting more and more serious. The doctor asks him to keep calm or his tumor may kill him. SING suddenly requests to transfer to another unit for he says that DING is acting against him all the time… SING invites KWAN for dinner and it suddenly rains after the meal. Coincidentally, JIT passes by in his car and SING deliberately takes good care of KWAN in front of JIT… The tycoon CHIN WING CHOI is committing adultery and a reporter has taken pictures of it. HIM and her reporter stay outside CHOI’s house to take pictures of him. On the next day, they are shocked to find that CHOI has died in the Jacuzzi.

HIM appears at the crime location and she says that CHI LUN is the murderer. She then takes out photos of LUN quarrelling with CHOI. The team carries out investigation and they discover that CHOI dies after drinking milk that contains cyanide. The team continues investigation in CHIN’s house and they reveals to LUN that CHOI was not killed in the Jacuzzi… DING believes that LUN is not the murderer and he releases her but SING thinks that DING is being biased. DING meets the person who delivers milk and the person says that he met someone strange before. Somebody sprays red oil on LUN and LUN reveals to DING that the tycoon MO YAU LEUNG may have done it. This is because YAU LEUNG used to invest in a Vietnam chemical plant with CHOI but the factory closed down after an accidental explosion. YAU LEUNG is killed in a hotel after drinking red wine that contains cyanide.

Everybody discuss the intention of the murderer and they believe that the two chemical plant owners are killed because they refused to make compensation after the explosion. HIM searches through the past records and she discovers that the engineer YUEN CHI MING was forced to take all the blame after the explosion while his wife and children are all killed during the accident. MING is wanted by the Vietnam police but he has disappeared after the incident. DING learns that the third chemical plant owner, MO YAU TAK, is returning Hong Kong for a funeral and this is a good chance to arrest the murderer. TAK is sent to the hospital after an injury and MING sneaks in successfully. YEUNG is safeguarding at the hospital and he finds SZ missing… SHUN joins a Halloween party and he discovers a horrible puppet on the tree. There are ID cards of three missing persons on the puppet……

The team discovers a tin house near the dead bodies and they carry out investigation there. CHAN AH PING and her disabled husband FONG YIU TSUN live there. PING claims that she is the murderer and she has killed her son as well… She says that she has done so for she doesn’t want others to ruin her relationship with TSUN. DING asks PING to recall the whole killing process but she is not able to do so… SZ reports to SING that PING has gone to an orphanage several times after killing her son… HIM visits PING at the detention room and she reveals the whereabouts of the abandoned baby to her. PING is heartbroken but she refuses to admit that she is a scapegoat. HIM returns home to find DING there. HIM is upset that DING refuses to get married and she wants to separate with him…

PING misses her son a lot and she finally reveals the truth to the lawyer. SING breaks into TSUN’s home without a search warrant but TSUN has already destroyed the evidence. SING threatens TSUN with a gun and DING arrives to stop him on time. SHUN informs SING that he is suspended from his duties… During their cold war, YEUNG insists to bring SZ to a demonstration unit. YEUNG has brought a new flat and he proposes marriage to SZ. TSUN is kidnapped at a Chinese medical clinic. The police search through the kennel outside TSUN’s house and DING asks the team to dig the ground under the kennel… DING receives an urgent message from YEUNG and he rushes to meet him. However, DING suffers from serious headache suddenly and he has to stay behind. When he catches up again, he finds that YEUNG is injured by gunshot already…

SHUN questions DING why TSUN and YEUNG are killed and DING decides to reveal the truth to him. However, SING says that DING is suffering from brain tumor and his judgments are not trustworthy… DING meets SZ and SZ finds YEUNG’s death very suspicious. DING decides to reveal the truth to her. DING suffers from headache again and he is sent to the hospital. When he wakes up, he finds HIM there. HIM receives an email with the photos of YEUNG being killed. She then receives a call and the person is trying to sell the video of the whole crime process to HIM for 500 thousand dollars… HIM asks SING out and she reveals that somebody is trying to sell her the video. SING is very nervous after hearing that… DING deliberately lets SING knows that a robbery happened nearby at the time when YEUNG was killed. He then pretends to be the robber to lure SING…

DING informs KWAN about the crimes that SING has committed. KWAN asks SING out and she wants him to start anew with her by leaving Hong Kong… SING suddenly receives a call from the drug addict LUNG and LUNG wants to sell the video to him for 1 million dollars. HIM receives a fax telling her that the informer is killed already. HIM follows the instructions and she finds the memory card but SING captures her. DING tells SING that he has no choice but to use stolen goods to frame him…SING meets up with DING. KWAN and LONG suddenly appear. They all persuade SING to surrender. SING captures KWAN and escapes successfully. DING follows them to a factory… DING captures SING eventually but SING reveals to DING that HIM is surrounded by time bomb and the bomb will explode very soon…