At some betting shop, while Sergeant Ko Lik-kei is agonizing over raising money for settling his girlfriend Tai Pik-kei’s debt, pickpocket Yuen Chun-tung snatches his wallet. Lik-kei and his subordinate go after Chun-tung. But Inspector Chung Ching-ying jeers at them as he is one step ahead. A witness called Lee Ho-fan goes to the police station to make statements. His legal counsel Lee Chung-ying insists that Ho-fan is not going to be a witness. She and Lik-kei keep arguing. Ho-fan picks up Lik-kei’s wallet in which he finds Lik-kei’s card. Ho-fan then calls Lik-kei. But because of Ho-fan’s stubborn character, Ho-fan and Lik-kei misunderstand each other. Ho-fan is the chairman of Rising Apparel Limited. He and his younger sister Chung-ying, who is a barrister by profession, are going to a product launch event hosted by senior staff member Yip Ming-kwan. Ho-fan accidentally causes Ming-kwan to embarrass himself at the event.

Lik-kei catches sight of Chun-tung while he and his subordinates are raiding some brothel. Lik-kei pursues him and reaches some unit. Ho-fan follows from behind and notices Chun-tung’s female accomplice. Chun-tung is restrained by Lik-kei in a back alley. Some assassin fatally shoots Chun-tung and even points a gun at Ho-fan. Lik-kei instinctively pulls Ho-fan away. But Ho-fan accidentally bruises his head and passes out. Ho-fan comes round and then cannot recall the course of events in the shooting incident. But he remembers he had seen Chun-tung’s female accomplice in the office. Lik-kei tells Ho-fan how to ask the company secretary to let him see CCTV footage, alerting Ming-kwan, Chung-ying and their chums. Lik-kei is then suspended from duty as Ching-ying zeros in on him. Lik-kei goes to see Ho-fan. He suspects someone is going to harm him. Suddenly, a gun-wielding mysterious person snipes at Ho-fan.

Lik-kei, Ho-fan and Chung-ying are evading the baddies. In an elevator, Lik-kei abruptly has breathing difficulties and collapses. After being pursued by assassin, Ho-fan keeps hiding in his room all day long. He is only willing to contact Lik-kei. Crime Unit tells Lik-kei to resume duty and protect Ho-fan. The duo are polar opposites and often get into hilarious situations. Ming-kwan is really scared as tough guy W wants him to settle his debt. To raise money, Ming-kwan uses some excuse for buying new machinery to embezzle company funds. But some document requires Ho-fan’s signature. Ho-fan refuses to sign as he notices some error on the document. Ming-kwan is frustrated. Lik-kei wants to track down the female accomplice mentioned by Ho-fan. He finds out Rising Apparel Limited has exactly lost the key date’s CCTV footage.

Lik-kei tries to help Ho-fan retrieve lost memories by forcing him to drink. Chung-ying is furious after finding out Lik-kei’s antics. Pik-kei is requested to repay her debt. Wing-yum’s home is doused with kerosene. Pik-kei gets nervous and calls Lik-kei and asks for help. Lik-kei tells his subordinate to stand in for him and protect Ho-fan. He then wants to rush home, resulting in some baddie seizing this chance to enter the place and shoot Ho-fan, who is on the brink of death. Chung-ying gets furious as Lik-kei has done a bad job. Ho-fan then unexpectedly wants to move into Lik-kei’s home. Wing-yum is annoyed as electrical appliances and furniture are repositioned. On Lik-kei’s advice, Chung-ying investigates the incident involving some snitch in the company. She also uses the CCTV hard disk to lure the snitch into showing up. Lik-kei takes Ho-fan to the police station. Ho-fan suddenly claims he is smelling the assassin’s odor.

At the police station, Lik-kei directs Ho-fan to look for the baddies. A certain target turns out to be Ching-ying’s subordinate. The case is concluded. Ho-fan and Chung-ying want to express their gratitude to the chums by inviting Lik-kei and his relatives and also his subordinates to dinner. During the proceedings, Chung-ying catches sight of Lik-kei and Pik-kei constantly clinging to each other. Ho-fan is bothered by regularly seeing images of Lik-kei in his head. He then makes an appointment with some psychotherapist. He also asks Lik-kei to help resolve issues of seeing him in his dreams. Wing-yum accidentally finds out Ho-fan is a committee member of the school where she works. She then uses him to save face in front of the principal. W asks Ming-kwan to settle his debt. However, Ming-kwan fails to convince Cheung-lok to sign the document for machinery purchase. Ming-kwan wants to kidnap Ho-fan and force Cheung-lok to sign the document on behalf of his boss.