Sai Yeung Choi Street in Mong Kok, Hong Kong, is lined with shops and crowded with tourists. The mobile phone stores of Ha Gong (Eric Tsang) and Shi Jian (Jacky Cheung) are across the street from each other. The two families use their own unique tactics to grab business and refuse to give in to each other. In fact, the two were good friends many years ago, and the story of their wits against the housekeeper is still passed down to this day, but...