DCS Ian St Clair est appelé à enquêter sur un meurtre tragique et inattendu dans une ancienne ville minière alors que la nouvelle du crime menace d'attiser les tensions historiques.

Alors que la chasse au tueur se poursuit, Kevin Salisbury du MET arrive pour aider à l'enquête. Et les tensions montent à mesure que le tueur tourmente davantage la communauté.

As Ian and Kevin are called to the scene of a second murder, news breaks of a former spy in the community at Gary’s memorial service. Meanwhile, Scott remains at large.

With two killers now on the run, Ian is forced to call in the Met to support the manhunt. Meanwhile, the hunt for the mystery spy cop intensifies as a link to Scott is found.

As the manhunt closes in on Scott and Andy’s location, the search for the spy cop turns the clock back to 1984 to reveal their identity and the events of that fateful night.

In a bid to protect those involved, Ian finds himself determined now more than ever to find the spy cop. The community attempts to heal in the wake of its loss.