Hong Kong pop singer-actress Sammi Cheng appears in cop comedy Lady Cop and Papa Crook, her first role on the big screen since Everlasting Regret. Opposite Cheng is another top Hong Kong pop singer Eason Chan. As long-time writing partners, Alan Mak and Felix Chong share writing credits for the hugely successful Infernal Affairs trilogy, Confession of Pain and the recent Overheard. The duo won best screenplay for the first Infernal Affairs at both the Hong Kong Film Awards and the Golden Bauhinia. John Fok (Eason Chan) is the kingpin of illegal red oil in China. When an oil tanker explodes accidentally, he becomes the focus of investigation by Hong Kong and Mainland Chinese police and is forced to halt his business to wait things out. Just as he is finally ready to turn his fortune around, however, his only son is kidnapped. Senior Inspector Molline Szeto (Sammi Cheng) is the rising star in the police force, who is well praised for busting crime with her characteristic sangfroid and precision. However, in matters of love, she is totally at wit's end. Poised at the crossroad of her life, she is thrilled to be assigned to investigate the kidnap of John's son. John dispatches his whole gang to ferret out his son's whereabouts, only to find out that his rivals are redeploying people in China to assail him. Just when he is about to order an all-out fight back, Molline suddenly arrives with her team to garrison at his house. Spurning her at first, he soon finds her critical analysis of the situation at hand both apt and useful. An unlikely cooperation between cops and crooks thus ensues, leading to conflicts and clashes galore at every step till the very end.