DCI Tom Mathias and DI Mared Rhys are confronted by a family in grief and a community in shock when they investigate the violent death of a local minister.

As the investigation into the murder of a local minister continues, the net tightens around the minister's daughter. And as the case is brought to a shattering close, Chief Superintendent Prosser is forced to confront an old foe.

Laura Dean, a curator, is discovered in a shallow grave in remote woodland. Mathias and his team must delve into the young victim's life to unearth some shocking secrets. Meanwhile, Prosser - still reeling from the death of Iwan Thomas - calls on the help of retired Chief Inspector Robert Owen.

A local man is the chief suspect in a fatal shooting at a remote petrol station. Tensions escalate when the suspect's young son disappears.

Desperate to find a missing boy and his killer father, DCI Mathias breaks protocol and sets off into the mountains alone. With the clock ticking, Mathias puts his life on the line.

The past comes back to haunt DCI Mathias as he investigates the death of convicted killer Catrin John - could her death be linked to that of Iwan Thomas's?

The past comes back to haunt DCI Mathias as he investigates the death of convicted killer Catrin John - could her death be linked to that of Iwan Thomas's?