A man meets a woman per chance and makes a bet with himself: he wants to start dating her in the next 100 days.

Inspector Lam investigates the brutal murder of Tsui, a famous musician. Wong, the designated suspect, just spent 20 years in jail for the murder of Tsui's daughter but has always claimed his innocence.

A young couple engage in a suicide pact, and slit their wrists together. However, only the woman, who is already suffering from cancer, dies. Three donors give her lover a life-saving blood transfusion. Each of the three has a rare blood type, and each has his, or her, own secrets. The trio become a target for the girl's vengeful spirit. Before matters are set right, the three victims will have been forced to donate far more than their blood.

Various government departments of the Hong Kong Special Administrative Region have been criticised heavily by the public. The Commissioner welcomes the proposal of "Sunshine Cops" from public relations officer Geena to enhance the image of Hong Kong's finest. Both Lemon and Sammy have recently completed their Police Tactical Unit (PTU) training. They look like movie stars and are fit and ready to conquer the world. They are selected to represent PTU in the internal audition for "Sunshine Cops" and contest against elite from other units like Criminal Investigation Department and Task Force, etc. The competition is tough but they prevail.