FONG TSUN KIT, Chief Immigration Assistant of the Immigration Department, is monitoring the travelers with his good friend LEUNG CHI LUN at Lo Wu Control Point. KIT married mainlander CHEUNG SZ MAN long time ago and his son travels to Hong Kong to attend kindergarten everyday. KIT’s mother CHAN MEI PING was a widow and she married the grocery shop owner CHUNG KWOK SING later. KIT and SING’s son CHUNG CHI WING have no blood relationship but they treat each other like real brothers. MAN and her son are granted the right of abode in Hong Kong and they plan to move in to SING’s house. Coincidentally, WING’s wife CHIU LAI MAN is pregnant and they plan to move back to SING’s house as well in order to save money. A woman called WONG KWAI HO hurts her ankle while helping to catch a thief at Lo Wu Control Point. Afterwards, she finds that her identity card is lost and KIT asks her son to pick her up……