Rewind many years and because of schizophrenia, Yeung Bik-sum (Kara Wai) almost fatally poisons her son Ip King-fung (Vincent Wong) and her daughter Ip Long-ching (Joey Thye). King-fung experiences seismic change and develops a split personality that manifests as intelligent weakling Chu Kei, who has always been a diligent student and eventually qualified as a graphologist. Chu Kei helps agile King-fung perform his undercover duties. A double bomb case and another blood writing naked corpse case prompt CIP Kong Ching-fun (Lai Lok Yi) to assemble a task force to pursue the perpetrators. The task force members are King-fung, psychiatrist Wai Yui-kit (Benjamin Yuen), pretty bomb disposal officer Yau Ngan-sing (Mandy Wong) and forensic anthropologist Fong Yuen-chin (Venus Wong). And the quartet even get involved in a romantic quintet. Father of criminal investigation Nip Shan (Philip Keung) recovers from bipolar disorder. He is assigned the task of overseeing the task force investigating all kinds of bewildering cases. But he finds out Bik-sum seems to be implicated in the mystery of his wife Leung Yat-sze's (Alice Chan) disappearance. While the maze is being unraveled piece by piece, how do the chums face up to the crunch?