Eye in the Sky takes place around the darker side of Hong Kong society, where the story begins with a group of organised burglars successfully robbing a jewelry store. The plot begins with the wet-behind-the-ears new recruit Piggy (Kate Tsui), who is plunged at the deep end in her first surveillance assignment working alongside her mentor, Sergeant Wong (Simon Yam). Both of them work for the Hong Kong Police Force's Criminal Intelligence Bureau.