Eric Tsang and stars are back with another entry into the "I Love Hong Kong" franchise this Chinese New Year with a story that is set in the 1970s, a decade of economic growth and prosperity for Hong Kong and the citizens.

After the hot-tempered police detective Fei messes up yet another operation, he is transferred to a fictional department that houses all the useless staff the force couldn’t sack. There he finds a new enemy in the mild-mannered desk officer Johnny, who loathes Fei’s disregard for discipline. But when Fei’s father and Johnny’s mother coincidentally become an item, the new brothers must somehow learn to cohabit under the same roof.