Geen and Hong are orphans raised by Wun Yee. When they were very young, their father had gambled away money reserved for use on Chinese New Year. Their mother had no choice but to resort to picking pockets. She was caught on her first attempt. The wallet that she had stolen happened to belong to a high ranking officer who was killed in a robbery attempt. She was charged with murder and subsequently hanged. The prosecutor who had wrongly accused her of the crime is Fung Sai Bong. The children's father commited suicide out of guilt and grief. The boys were then placed in the care of their father's boss and his wife Wun Yee. The couple already were foster parents to a pair of young orphans. Not long after the boys moved in, Wun Yee's husband died of a heart attack, leaving her to raise the four children on her own. She tried to seek help from her brother-in-law in Macau but was given the cold shoulder and turned away. She resorted to working several low paying jobs and managed to raise the children on her own living on meager means.

While growing up, Geen had to quit school very early on to work and help Wun Yee raise his younger siblings. Hong is now an aspiring law student at HKU. During a TV program which explores the life experiences of three different persons born on exactly the same day, Geen meets Guan for the first time and they soon become good friends.

Wun Yee's niece, Wah, from Macau moves over to stay with the family due to their proximity to Hong Kong University. Wah is very fond of Hong who takes advantage of the fact to make her do chores for him. Geen who is secretly in love with Wah is angry that Hong should treat Wah this way. While arguing over this in the car one night, they get into an accident in which Hong suffers permanent damage to his legs. Mun and her boyfriend, both practising medical students, come to their aid.

Missing classes and unable to catch up with this studies, Hong decides to quit school and work for Fung Sai Bong, under Fung's eldest son.

With Hong behind the wheel, Fong's eldest son gets into a heated argument with Guan's brother, a company rival, and makes Hong run the car over him. At the advice of his father Bong, he and Hong changes the car's licence plates and drives the car into a lake.

Hong returns home to Geen and tells him that he had run over a man thinking it was an animal. He urges Geen to assume guilt for him reminding him that he had promised their mother that he will take good care of him forever. When police shows up at their door, Geen confesses to the crime only to find out that Guan's brother was physically attacked before his death and his cause of death was actually loss of blood. Had he received immediate medical attention, he may not have died. He confronts Hong and lets the family in on Hong's doings but Hong threatens that it is too late for him to retract his confession. Geen is subsequently sentenced to two years in prison for a crime that he did not commit.

In the meantime, Hong attempts to win Mun over from her boyfriend, causing her already paranoid and insecure boyfriend to suffer a nervous breakdown. However, when he meets Bong's daughter Fung Mei Yan, he decides to jilt Mun for Mei Yan instead. When Mun tells him that she is pregnant with his child and refuses to leave him, he plots to murder her. During a trip to Malaysia, he throws her off a moving train after making her write a fake suicide note under the disguise of a letter written to a depressed friend. What he did not know is that Mun had written a suicide note two days earlier and had put it in her sweater pocket when Hong interrrupted her with a promising phone call.

Geen is released from prison and starts a food vending business with several of his ex-inmates. Guan secretly sponsors his share of the capital and allows him to pay in installments.

Geen and Wah slowly finds themselves drifting further and further apart. Wah is afraid that they may end up breaking up so she decides that they should get married right away. On their wedding day, Geen comes across a letter in which Wah confides to a friend that she is unsure about her relationship with Geen. Geen decides not to go through with the wedding. Trying to put the matter behind them, Wah leaves HK to pursue a career in Malaysia, and Geen takes up a job in the middle east. But when Geen learns from Guan's colleague that she has been secretly in love with him all these years, he decides to stay back and be with Guan.

When Wun Yee visits Mun's mother in Malaysia, she accidentally discovers Mun's sucide note. She confronts Hong who was making a stopover visit after a business meeting in Singapore. When Hong learns about the second suicide note, he frantically demands the note from Wun Yee and when she cannot produce it, he kills Wun Yee in a fit of rage.

When news that Wun Yee is missing travels to Hong Kong, Geen flies to Malaysia and enlists the help of Wah to find Wun Yee. Based on eye witness accounts from a taxi driver, a hotel receptionist, and an Indian boy who took Wun Yee's bracelet from the crime scene, they conclude that Hong had killed Wun Yee. When Hong is tried in HK to decide if he should be extradited to Malaysia for prosecution, Hong manages to avoid extradition through a technicality in the law that says that eyewitness accounts written in English are not reliable when none of the witness know how to read or write in English. He also vows he will never step foot on Malaysian soil and Geen and the rest would never be able to prosecute him.

When Mei Yan learns that Hong had killed Wun Yee, she tries to leave Hong but Hong would not allow it and begins to harass and extort money from her. Unable to withstand the mental turmoil, she commits suicide, leaving her baby in her father's care.

With the money that he extorted from Mei Yan, Hong starts his own company but suffers major losses in the stock market. He kidnaps his own son and demands $10 million rom Fung Sai Bong. When the police tries to arrest him, he attempts to leave HK by boat but does not have enough money to do so. He shows up at his sister's house to demand money but runs into Geen, and they get into a fight where he falls down an elevator shaft and breaks his leg.

Wah continues to hope that Geen will come back to her but Geen informs her of his upcoming wedding to Guan. Wah finally comes to accept it and gives them her blessings but on the night of the wedding, she commits suicide and dies.

Several years later, Geen and Guan has a son. Geen joins Guan's family business and becomes a top executive. When Geen sees Hong living on the streets, he offers him a job at one of his restaurants, much to the disapproval of Guan. Hong attempts to kill Geens' family by poisoning them during a family dinner. Guan and Geen survive but their son and six others die. When Geen learns from his lawyer that the sole heir to his estate upon the death of his whole family would be his brother, he becomes highly suspicious of Hong. His fears are confirmed when he finds a bugging device hidden underneath his phone which mysteriously disappears right after Hong's second visit to his house. He vows to make Hong pay for everything.

Working without his wife's knowledge, Geen promotes Hong to an executive positon and gives him an assignment to work in Australia. Using delay tactics, and changing to another flight on short notice, he manages to trap Hong on a flight that makes a stopover at Malaysia. Hong is finally brought to justice.

When Guan learns what had happened, she attributes her son's death to Geen giving Hong another chance to be near them. She leaves him for volunteer work in Africa. When Geen pleads with her to come back soon, she promises she would return ten years later on their birthday to the church where they got married. But in the final scene, when she fails to return on that promised day, a tired Geen is shown to have fallen asleep on the church bench when a mysterious woman walks up to him and leaves him a note that says "Guan has died, please forget."