The climax of the first series saw DCI Tom Mathias pushed to the edge; with a local woman's death on his conscience and blood on his hands, the series came to a dramatic end with Mathias' future hanging in the balance.

Mathias' struggle to differentiate between his professional duties and personal feelings should have left his career in tatters, but Chief Superintendent Prosser has other ideas, and the one-off special episode begins with Mathias' difficult return.

DI Mared Rhys, who has led the team in Mathias' absence, is forced to step aside as her old boss investigates an arson attack on an isolated farmhouse. An attack that has left a mother and child fighting for their lives.

As the investigation unfolds Mathias is drawn into a community of failing farms, festering resentments and long standing feuds. Suspicion falls on several in the community, including the victim's husband - a local timber merchant who was unscathed by the attack - and a young man displaced by the closure of his farm.

With lives hanging in the balance, Mathias is forced to act, but what is it about this case of a mother and child that draws him in, pulling him back from the brink? Could it be a connection with his dark and troubled past?