Immigration Department is guarding the door of Hong Kong, and seeks out to prevent doubtful identities and criminals from entering Hong Kong. It only not creates a highly demanding task for immigration officer and also raises a further question – how will they make identity verification as accurate as possible?
FONG TSUN KIT (Kwok Chun On) becomes friends with two other candidates CHENG PAK YUE (Cho Wing Lim)   and YIP ON KEI (Mung Ka Wai, Yoyo) while applying for a post in the Immigration Department. YUE is an aggressive person. He later moves to the Police Force and is promoted to Senior Inspector of Regional Crime Unit. While investigating a murder case, he realizes that the new gang leader WU KIT SUM (Wong Tak Bun) has killed somebody because of KIT's wife. It totally turns KIT's life upside down. As a good friend, KEI helps KIT take care of his son after a failed relationship with YUE. When two hearts meet, an extraordinary link spontaneously draws them together. Meanwhile, AU SHUN FUNG (Patrick Tang) appreciates KIT's ability very much and recommends him to MAK KAI MING (John Chiang), Head of Investigation Section. KIT gains approval and he is determined to start anew. While carrying out an investigation on a fraud syndicate, he comes upon his missing wife and uncovers her long-hidden identity…