Tom Chan, Dick Ching and his older cousin Hairy Mo live in the same tenement building but each of their love life is different. Tom and his girlfriend Joyce are totally harmonic, but nonetheless love have become feelings. During one time looking for lust in a nightclub, Tom meets a stunning PR girl, Cat. The two fall in love with each other but since Tom's weeding date is getting close, he needs to make a tough decision. Dick is a playboy who often pursues sex without love. Sometimes at night without a pursuing object, Dick would spend the night with Wai-fong. At this point, Tom's younger sister, Pearl, returns to Hong Kong from the US and Dick feels lost of Pearl's passion. On the other hand, Dick realizes that he had always loved Wai-fong but she has gone elsewhere when he wants to express his love. Hairy is a bachelor who meets a divorce man Michelle, who turns out to be a homosexual man. Later, Hairy dates a girl named Francis who strikingly resembles his idol Vivian Chow, something unexpectedly for this unbearably lonely man.
The Special Duties Unit (SDU) is an elite paramilitary tactical unit of the Hong Kong Police Force and is considered one of the world's finest in its role. But being the best carries its own burdens. Like everyone else, they go through troubles with love, with family and with their jobs. And sometimes they get horny.
The story takes place in Tai Hom Village, a small Hong Kong shantytown that is literally and figuratively overshadowed by a large apartment and mall complex called Plaza Hollywood. The movie begins with pig butcher, Mr. Chu (Glen Chin) and his sons, Tiny (Leung Sze Ping) and Ming (Ho Sai Man) who are all obese. Keung (Won You Nam), also a resident of the town, is preoccupied with internet porn which leads him to meet Mainland Chinese prostitute Hung Hung (Zhou Xun), who advertises her services online and whom he pays for a night of torrid sex in the bushes outside Plaza Hollywood.
Johnny Du Kei-Fung (Wong Cho-Lam) is a Hong Kong detective who dreams of becoming a member of the exclusive G4 Team that protects the city's Chief Executive (Patrick Dunn). Johnny is deemed too short for the team and his application is denied. At home, Johnny is bullied by his girlfriend Angel (Kimmy Tong) as weak and unsuccessful.
As Lunar New Year 2012 marks the year of the Dragon, the film explores the Chinese's age-old obsession with the Dragon and having children on a "Dragon year" (see Chinese zodiac). In the introduction, Ah Long (Melvin Sia) tells about how his father (Zheng Geping) was desperate to have a son born in the Dragon year because his ancestors had decreed that only a "Dragon boy" could take over family's lion dance association. His mother (younger, Pan Lingling and older, Lai Meng) instead gives birth to "Dragon girls" while Ah Long himself was born several seconds after the clock struck twelve, making him a "Snake baby", much to the disappointment of his father.