A bright environment does not mean that darkness does not exist, a peaceful society does not mean that danger does not exist. This era needs a vigilant society to be prepared for emergencies and unexpected events. Although natural disasters and violent acts cause people to panic, the scariest is actually people's mind. As such, decisive action must be taken to stop these terrorists from creating trouble in society, including
Hong Kong itself. After an encounter with some terrorists and barely making out of the scene alive, Carson and Alfred, two brothers raised by their widowed mother Tong Shuk-fun, join the ATF together, an agency under the
Security Bureau (Hong Kong). Each specialising in a different talent, Carson succeeds in the force's intelligence unit while Alfred joins ATF's operations unit. With both brothers earning the respect and trust of their superior, ACP Steve Shum, Shuk-fun thought that it was finally time for her to retire in peace. However, after receiving a piece of intelligence, the two brothers suddenly change sides and become enemies. Carson discovers reliable information about a secret organization through journalist Yip Ting, and he almost loses his life investigating it. Yip Ting saves Carson but Carson is exposed of his lies as he attempts to protect Yip Ting. Carson attempts to seek revenge as the ATF members believe he has strayed to their enemy's side. Unable to reinstate himself back in the team, he convinces his girlfriend Jessica, an intelligence analyst for ATF, to secretly obtain information from the force's database to help with his investigation. Carson later bombs the ATF headquarters but find out afterwards he had been seeking help from someone who he thought was a friend of his. With details of the case leaking to the opposing organization, Alfred believes that his brother is the mole. Meanwhile, Carson focuses his efforts on luring the real mole, abandoning all ethics in the process. The situation worsens as it is believed that the secret organisation in
Hong Kong plans to spread a virus and earn money from it. Would the ATF be able to stop them before they infect the entire world? ==Main cast==