Former CID detective Kevin Cheng was forced to leave the police force due to suspicions that he was involved in an arson case. He joins a security company, where he meets Ruco Chan. As a former detective, Kevin has a reclusive character, but has a sharp eye that can catch tiny details from surveillance footage which are often the key to solving cases. Ruco's thinking and style of working is similar to Kevin's and is also excellent at his job. The two become good friends and are looked upon favourably by their superior Lau Kong. This is until private investigator Tavia Yeung appears. Conflict arises when she mistakes Kevin for an old friend. It causes him to recall a long-forgotten incident, which turns out to be related to the arson case. Tavia, known to possess a human "eye in the sky", continues to investigate along with Kevin and Ruco, but as they get closer to the truth, the conflict between emotions and the law grow more fierce and the relationship between the three of them experience a big change...