Highton prison sits nestled within the moors of western Cumbria, close to the coastal road. When two former inmates turn up dead, DI Kelly Porter is tasked with finding out why. It soon becomes obvious that she is hunting for one killer and the place where both victims were incarcerated holds the key. As Kelly delves into life at Highton she finds more questions than answers. A web of corruption and deceit emerges within the prison walls.
As Kelly gets closer to unpicking the relationships between the officers and their wards, a full scale prison riot explodes – with police caught in the middle. Kelly now faces a hostage situation with a well-loved member of her team caught in the middle.