Armed Reaction IV

The series takes place a few months after the 3rd installment.

Chan Siu Sang (Bobby Au-Yeung) and Wai Ying Zi (Ada Choi) have been dating for a while and seems to be in a stable relationship. Everything seems to be looking up for Ying Zi now that she's in a stable relationship and finally got a promotion at work, but the only thing that she and Siu Sang seem to fight about is marriage. He wants to rush into marriage but she wants to put it off for a few years to focus on her career since it is flourishing. Their relationship is further complicated when Siu Sang becomes jealous of Ying Zi's new handsome co-worker Ken (Frankie Lam), and Ying Zi becomes mad that Siu Sang does not trust her, so the two decide to break up. Ying Zi soon starts dating Ken since the two grew close while working together and Siu Sang begins dating Sunnie (Yoyo Mung) who works at the forensic department after being pursued by her.

Having gone through so many tragedies in the past Chan Sam Yuen (Joyce Tang) finally decides to focus on her family as top priority. She and Ching Fung (Marco Ngai) have patched up their marriage even though it is still not perfect. With a difficult pregnancy Sum Yuen is no longer focus on her career. All seems well with her and Fung when she gives birth to a son until Fung gets entangled with female triad boss Chiang Tin Wing and her husband Sing Jin Choi. Fung is in charge of the case of Wing and her crime empire. While investigating Wing, she takes a liking to Fung and drugs him so she can have her ways with him. She uses their one night of passion to blackmail Fung into continuing their affair. Choi finds out about the affair between his wife and Fung, enraged with his wife's infidelity he accidentally kills her and frames Fung for her murder. With evidence to clear Fung of the crime Choi decides to kill Fung as revenge for ruining his marriage.[1][2]

• The fourth series continues with Ada Choi as the female lead actress.
• Same as the previous installments of the series some of the supporting actors in the first two series play completely different characters in this series with no relations to the characters they previously played.

Armed Reaction IV received much complaints about the story not tying back to Armed Reaction III.

• It was mentioned that Chan Sam Yuen became pregnant at the end of Armed Reaction III. In the early episodes of Armed Reaction IV she is 7 months pregnant. Chan Sam Yuen and Ching Fung's daughter Ching Sa Sa was only four years old in Armed Reaction III, but in Armed Reaction IV she is a preteen. Audiences complained that the rapid aging of Ching Sa Sa did not make sense.
• In Armed Reaction III Wai Ying Zi had promised that she would marry Chan Siu-Sang when she receives the "gold whistle" (an Hong Kong Police award), but in Armed Reaction IV when she receives the "gold whistle", she does not marry Chan Siu-Sang and her promise is not mentioned. (However, the complaint is unfounded because in the first episode Wai Ying Zi mentioned that she will marry Chan Siu Sang after she gets promoted and used the "gold whistle" as a symbol of their promise)
• Tung Ka Fai promised his wife Chan Sei Hei that he would stay and work in Hong Kong in Armed Reaction III, but in the 4th series he is constantly traveling overseas for work.
• At the end of Armed Reaction III Chan Ng Fuk and Au Chi Keung got engaged but in Armed Reaction IV they are only still dating.
• Ching Fung's whereabouts were left without any conclusion. As Armed Reaction IV ended the other main characters were still searching for him. In the last episode, however, officers in Kat O island found his whereabouts.

• TVB Official Website (in Chinese)