"A Rich Merchant kidnaps his own son, what is this all for?"

Serious Crime Squad CID Sung Ka Fai (Steven Ma) is has great respect for his brother-in-law Shum Chi Leung (Ng Ngai Cheung). The reason for Fai's admiration is not because of Leung's success in business, but is because of his love and protection towards Fai's sister Hiu Ying (Elaine Ng). Leung also looked after her family in the past, funding Fai to complete his university study.

Leung asks Fai to help him look after his business and just as Fai is about to resign, the son of stock market hunter Kwok Wai Fung (Lau Dan) is kidnapped, together with Leung's son. For professional and personal reasons, Fai hopes to catch the kidnappers. On the surface, the case seems to be connected with Triad linked Ching Wai (Ngai Wai). The kidnappers demand that Leung himself goes to pay the ransom so he follows the instructions and throws the box with the ransom inside into the sea, where it disappears...

Finally, Leung's son is rescued, but Fung's son is murdered. Not long later, the police also find the body of Wai. Who is the real mastermind behind this?