Widow TONG SUK-FAN (Louise Lee) is saddled with hardship alone, struggling to bring up her two sons CHONG YAU-CHING (Ruco Chan) and CHONG YAU-KIT (Ron Ng).
The brothers join the Intelligence Unit and the Operations Unit of Anti-Terrorist Force respectively, and both gain recognition from their superior SHUM CHI-NGO (Eddie Kwan), which is supposed to be a comfort to their mother. Unexpectedly, their brotherhood is turned to enmity owing to an intelligence. Through a reliable source from a journalist YIP TING (Yoyo Mung), YAU-CHING probes into a secret organization, during which he nearly gets himself killed and cannot resume duty immediately.
After seeking aid from his girlfriend CHUNG YAT-KA (Aimee Chan), who accesses the database in secret by leveraging her duty as the intelligence analyst, he uncovers that there is a mole in the intelligence agency. His younger brother YAU-KIT not only suspects him of being a traitor, but also takes advantage of his absence to court YAT-KA. Just as YAU-CHING is caught helplessly in a dilemma, fortunately, he gets help from YIP TING, and the two gradually develop romantic feelings for each other.
However, in an attempt to ferret out the culprit, YAU-CHING does not hesitate to use himself as the bait, walking to the path of no return. Long-gone seems to be the days when fidelity, love and righteousness still mattered to him...