Wao, aged eighteen, in an occasion, she rescues Sergeant Chung and his followers. Wao joins the police force because of the high salary. To express their gratitude, Chung etc return to the police-teaching academy and assist her to graduate successfully. She joins their team, they spoil her and the spirit of the team is very low. High-ranking officer Madam Lui sends Izu to spy on them and photographs their "criminal evidence". Wao attracts by Izu and he calls her to co-operates with him in the "mission". To assist Wao joins the Japan's Interpol Internship Scheme, Sergeant Chung etc become hard working and want to make a "big case". Laughs burst out because of their innocent on Izu's mission, and also their operations in the "big case".