This story continues from Armed Reaction III by following our 4 main characters, Chen Siu Sang, Wai Ying Zi, Chen Sam Yuen, and Ching Fung in their roles as enforcers of justice and emotionally involved men and women.

Wai Ying Zhi's performance at work has given her confidence and her relationship with Siu Sang is now stable. However, a gap starts to form in their relationship as Siu Sung is very eager to get a married and start a family while Ying Zhi wants to focus on her career and get promoted to an inspector ranking first.

On the other hand, Chen Sam Yuen is pregnant and has been temporarily transferred to the Traffic Formation wing while waiting for the upcoming birth. After experiencing all of these hardships, Sam Yuen has developed a new way of thinking and philosophy towards life. The once extremely career driven Sam Yuen's new focus is now on the family, her husband, and her daughter. She is now truly a little housewife. Her husband Ching Fung's career is reaching new heights as he is promoted to Chief Inspector.

The criminal investigation part of the series involves Fung's Special Investigation Unit gaining evidence against the triad group Hung Ying.

Health and Bobby took great pains to end hold beauty go with the attitude Ada Fu cohabitation , emotional stability . Raw desire for an early marriage , but the posture is to focus on the cause of delays . Health and marriage unrealized dream , the nightmare is coming up, posture around emerging bees , butterflies wave , first Raymond , after the spoiled rich kid, Chen Jiaxi Crime Unit Superintendent Kwong Tsz key , Frankie Lam . Posture actually still love the students , but hate his favorite style, dry vinegar spate of conflict and misunderstanding with the Health , placing the end to break .
Posture and used to be just ordinary relationship between colleagues , and students break up gradually found that the key advantages and alternate Sentiment . Health Seeing posture , launched a new romance, bitter pill to swallow . At the same time , he found that the Forensic Science Division forensic Fangqing Yoyo Mung , director of the original has been a crush on . ...
On the other hand , ternary Joyce was pregnant again , he was diagnosed with toxemia of pregnancy , to keep the fetus have to gamble with their lives . Peak Marco Ngai facing a major crisis of the family I , the other is to crack down on gang Hung Ying community . Good and evil and conflict of intense Jiangtian Ying Cheung Wai Yee , Hung Ying society leading to the peak affection , followed by Ying killed peak accused murderer caught in utter hopelessness . ...