Al Cappuccino

Cheung Sai Lun is a struggling actor from Ohio with Hong Kong heritage comes back to Hong Kong to audition for a role in a film. However, he is wrapped up in a murder case involving the murder of triad boss: Old Chiang and his 2 sons. He is asked by Rachel Koo, a senior inspector of OCTB, to become a spy in a triad for the police alongside the pre-existing spy: Ko Ban. He is cast as the Chiangs' long lost third son with the fact that the real son had been killed in a gang war beforehand. Cheung soon gets to know the three Chiang sisters: Chiang Chin Ha, Chiang Chin Yu and Chiang Chin Wai as well as their uncle: Lui Ka Cheong and begins living with them.
(Source: tvbanywherena.com)