Season 1

When he was younger, Ko Yat Tai infiltrated the triads as an undercover agent. The triad leader's daughter, Lou Man Na, fell in love with him at first sight. Although Ko Yat Tai already had his heart set on Lee Ying Lan, he pretended to be with Lou Man Na to solve the case During a fight between triads, Ko Yat Tai eliminated Lou Man Na's triad rivals, but Lou Man Na's fate remained unclear. Ko Yat Tai's good friend, Nip Yu Hong, knows about his affair with Lou Man Na and their infant son Ko Ka Long. Ko Yat Tai brings Ko Ka Long home, and Lee Ying Lan also gives birth to a son Ko Ka Chu. The half-brothers accumulate a number of grudges growing up. Both also coincidentally develops a father-like mentor relationship with Nip Yu Hong. During a promotion ceremony, Ko Yat Tai, having achieved the rank of Superintendent, is happily preparing to receive this honour but unknowingly steps into a revenge plot that is 30 years in the making.