Dr. Ko Lap-yan heads a team of senior psychiatrists and residents at the Yan Wo Hospital in Hong Kong. Most episodes revolve around the team diagnosing patients. With a specialty at diagnosing criminals, Ko also has close ties with the Serious Crime Unit of the Hong Kong Police Force, a unit headed by Senior Inspector Chung Kwon-ban. The second series sees Ko's resignation from the Yan Wo Hospital; he is later transferred to a new psychiatric department, the Forensics Psychiatry Department, of Bok On Hospital, where he formally diagnoses criminals.

Kung and Kin's rivalry goes way back to the seventies when they fought over the same girl, who eventually became Kung's wife. Now they run competing phone stores right across from each other on Mongkok's busiest street, and stretch their minds trying to outdo each other with crazy promotions.

After his business goes bust, Ng Shun and his family move back to his old apartment to stay with his father. He has not returned for 10 years because the apartment is too small for his family. Furthermore, the environment is unfamiliar to Shun's family. Coincidentally Shun's old childhood friend, Lung returns too. Due to an old misunderstanding, Shun is distrustful of Lung. Will Lung regain Shun's trust again?

Laughing is formally a police undercover. However due to a drug trafficking case, Inspector Pan is hot on his trails. Before Laughing becomes a police undercover, he works under triad leader Yi. Yi treats Laughing as his own brother, however to protect his territory and illegal businesses, Yi instructed Laughing to join the police force and act as his undercover. Laughing is a high-flyer in the police academy. However he never got a chance to join the force because he is specially picked by Inspector Xian to be an undercover in the underworld syndicate. Hence Laughing becomes a “double-undercover”. Yi is happy that Laughing is allocated to the triad of his rival. To make his situation worse, Laughing falls in love with the triad leader’s sister, Karen. Justice, brotherhood and love, what will Laughing decide on? His decision will be a turning point in his life.

Chinese Feng Shui master Carson was a "Natural Born Player", taking names and breaking hearts. Fate had it that he would meet his match, the hot veterinarian Chi-Ling. It was love at first sight but neither could stand the other's fickle nature lest the affair might have ended as soon as it began. Chi-Ling's roommates, Big S and Small S came up with a perfect plan – to invite Carson to move in with Chi-Ling and make him promise to have no sexual contact with any girls for 100 days. Carson accepted the challenge without a second thought. Yet, the two sisters and his ex-lovers took turns in seducing him. Ninety difficult days have since passed, the biggest temptation arrived in the form of the hottest bachelor in Hong Kong, Daniel Lee began courting Chi-Ling. At the same time, Karen, Carson’s first love, suddenly came back into his life. Would these star crossed lovers cross the finish line together?

A female police officer goes undercover as a beauty pageant contestant to protect a key witness.