A body is found on a beach in North Devon; DI Matthew Venn and his team search for a way into a case that has no witnesses, no forensics and no motive.

Connections are made between the victim and the Brethren community when it's uncovered that the victim had started attending meetings; the pressure of the case intensifies and finally, the team are afforded some vital break-throughs.

The prospect of rebuilding a relationship with his mother blurs Matthew's ability to objectively examine the Brethren community; Lucy and Gaby can no longer stay quiet as an important silence breaks, with the revelations that follow, no one is safe.

Despite key breakthroughs, the team are frustrated until an important piece of evidence sets Matthew on the path to finding the murderer; Matthew has a chance to solve the case with the killer in his sights.