When elementary school teacher Gemma Hillman disappears into thin air, DC Martin King decides to set up his observation post at the home of single mother Zoe Sterling. His reasoning is simple: Zoe's flat offers a panoramic view of all the comings and goings of Westbury Square. More specifically, he can see right into the flat Gemma shares with boyfriend Greg Sullivan - the prime suspect in her disappearance. But Martin is a man who carries his own burden of trauma and guilt and he begins to wonder if he can trust what he perceives? Could he project his own loneliness and remorse on the disowned Greg?