Sworn spinster LEUNG SUM runs into TAI-KOON from a wealthy family while going grocery shopping, so she warns AUNTIE CHAI, who looks after TAI-KOON, to be wary of the recent surge in kidnappings. Unexpectedly, TAI-KOON is still abducted. After SHUM YAT-YIN, a brave and honest detective, arrests a thief on the street, he comes across his co-worker KAM WAH, who out of the blue starts defending the thief. KAM WAH sees someone holding a kid, and his furtive behaviour smells fishy to KAM WAH, who immediately runs after them. As their newly appointed supervisor from Britain pays much attention to the child abduction case, Detective Inspector LUI KWOK demands all the detectives to cancel their vacation and probe into the matter. Having taken bribes, KAM WAH distributes the money to the others, but YAT-YIN refuses to accept the money……

When KAM WAH goes to TAI-KOON's residence to collect the rest of the bounty after he successfully saves the child, he is spotted by AUNTIE CHAI, who immediately tells LEUNG SUM about it. Fishmonger MASTER PO comes to visit YING-YUET, so KAM WAH pretends to plan a banquet treat for YING-YUET, managing to deceive MASTER PO into treating YING-YUET to a banquet the next day. CHONG NGO-SHAN is the boss of the Shui Fung Nin Rice Store; whereas his concubine HO WAN-FONG is his right-hand woman. Suspecting that someone stole the rice, WAN-FONG comes up with an idea and easily makes the criminal give himself away. By coincidence, MAN-TO also plans a banquet treat for CHOI-TIP, so YUK-KIU tells YING-YUET to alter her schedule. That greatly exasperates MASTER PO, who even challenges MAN-TO to a competition to burn banknotes during the banquet……

YAT-YIN is reassigned to an idle position, and he comes across LEUNG SUM while looking for a lost dog named ROSE. LEUNG SUM mentions her background, so YAT-YIN suggests that she could post a notice in a newspaper to look for her family. LEUNG SUM's mentor, MEI-LAN, used to look after a girl called SOPHIE, who got married in Britain and recently follows her husband CHARLTON to return to Hong Kong because of her husband's job relocation. SOPHIE also pays LEUNG SUM $5 a day to cook for them. After leaving the newspaper office, LEUNG SUM and YAT-YIN bump into a mentally ill woman, MADAM LEUNG, during which YAT-YIN even helps her locate the whereabouts of her husband SZETO CHI-LEUNG. Therefore, they get to know the boss of a trading company, NG SAI-CHEONG. KAM WAH owes $500 in gambling debt, so he comes up with an idea……

With all the prostitutes of Foon Tak gathering in the lobby, YUK-KIU and CHOI-TIP respectively pressure YING-YUET to tell KAM WAH to return the money to them. SHEK KAU reads the family tracing notice posted by LEUNG SUM, so all of them start guessing which part on her body her birthmark occurs. YING-YUET happens to look for KAM WAH, who turns out to have sneaked into LEUNG SUM's home and peeked at her birthmark. Suddenly, YING-YUET and LEUNG SUM have a quarrel, during which YING-YUET blames LEUNG SUM again for having caused them to be kidnapped years ago. Having gone into debt by gambling at a casino, KAM WAH is under SAI-CHEONG's threats to work for him. All the prostitutes from the four big brothels assemble outside of the residence of the Commissioner on Banning of Prostitution, requesting to meet up with him, but SOPHIE refuses to let them in……

YAT-YIN manages to rescue CHI-LEUNG from SAI-CHEONG's henchmen all by himself and flees. Midway through, he runs into MADAM LEUNG and LEUNG SUM, so YAT-YIN guides them to take shelter in a safe place for the time being. Upon his return to the police station, YAT-YIN directly reports to his supervisor, a westerner, with regard to the situation of CHI-LEUNG and human trafficking, above which he even successfully convinces his supervisor to go to the safe house in person. However, when they arrive there, they find the house empty. With the prostitutes from the big four brothels once again gathering outside of the commissioner's residence, SOPHIE is unable to resist enormous pressure from the masses anymore, so she expresses that the commissioner, CHARLTON, agrees to give them a five-year buffer period. Through his investigation, YAT-YIN surprisingly uncovers that NGO-SHAN asked SAI-CHEONG to help look for his long lost biological son……