As East Sussex police bid farewell to ACC Alison Vosper, the announcement of her replacement is not welcome news for Roy Grace (John Simm). Shaken by the recent sighting of Sandy, Roy attempts to get closer to the truth while trying to move forward with Cleo, as he is drawn into three sinister investigations. A chilling serial offender from Grace's past, a road traffic accident which unleashes a web of vengeance and a shocking murder attempt of the Brighton music scene, all test Grace's skill as past and present collide for Roy, forcing him to confront old memories and learn from previous mistakes.