A world of narcotics is what bonds these people co-existing from different worlds.
Heung Wing/Gordon Heung (Michael Miu) is the Narcotics Bureau’s Operation Wing senior inspector who is also a mentor and good friend to Wai Sai Lok/Happy Sir (Raymond Lam), the senior inspector of the Criminal Investigation Bureau (CIB). Together, they work hand in hand to solve various cases.
Yu Wing Tung/Helen (Elaine Ng) is Gordon’s ex-wife who separated from him because they had very different views towards their work ethics. As a result, they gradually grew apart and ultimately separated due to personality clashes. However, fate has it that Wing Tung returns to Hong Kong as the chief inspector of the Financial Investigation Bureau that works hand in hand with the Narcotics Bureau. The two begin to spend more time with each other and subsequently reignite their former burning candle with each other.
Gordon is a friend’s man who is always constantly on the lookout for his friends. After a mysterious man threatened to reveal his good friend’s illegal money laundering business, he had no choice but to partake in illegal drug manufacturing and trafficking, cooperating with major criminals.
During a drug bust, Sai Lok discovers crucial and disturbing evidence that hints Gordon’s illegal act. As an upright officer, he must put aside his personal feelings and quietly begins to investigate this matter further. This slowly causes the downfall of this former close friendship. Organised Crime and Triad Bureau chief inspector and later the chief inspector of the Operations Wing as well as work and romance rival to Sai Lok, Poon Hok Lai/Brian (Ben Wong), soon discovers Gordon’s illegal act and decides to use this chance to create further suspicion between the friends when he creates even more conflict for them.
In the mist of all this, Sai Lok finds his life getting entangled with informat Chan Ka Bik/Pat (Kate Tsui). She is merely a girl who suffers from low self-esteem due to her humble childhood. She lives with her flatmate and friend Ng Tak Tim/Tim (MC Jin) who has a crush on her. She would do any job that pops up to earn money to support her younger ill brother, even if it means putting her life on the line. Mutal love sparks between her and Sai Lok but their relationship is anything but smooth sailing. Sai Lok’s subordinate, Ko Hei Seun/Sandy (Ella Koon), finds herself falling for him. Hok Lai discovers Sai Lok’s relationship with Ka Bik and convinces her to leave him. So she decides to withdraw out of this love triangle as she deems herself unsuitable for Sai Lok. However, this relationship only continues to grow more intertwined when Hok Lai decides to enter the equation pursing Sandy.
Left with nothing to lose, Ka Bik turns to narcotics and soon that takes over her life. She becomes a drug dealer and rises in ranks earning herself the formidable title of “Drug Queen” who runs her life without regards to the law.
Pained by her actions, Sai Lok puts aside his feelings for Ka Bik and cooperates with Gordon to bring down her narcotics operations. However, a price must be paid for this painful mission. What will this price be? Who will be the real winner of all this?