The team start building the case against their main suspect, but in a shocking development, an armed man enters the frame.

After the school shooting, the gunman is charged with murder. Ffion is convinced Mel could have been involved in the historic murders and clashes with Rick, who tries to keep the past under wraps.

Ffion and Rick’s relationship intensifies as the past continues to haunt the present. Ffion discovers a devastating secret that changes everything. And a new suspect emerges.

Rick arrives home and panics when Helen is nowhere to be found. With the clock ticking. Ffion follows her gut, back to the bunkers near Cleddau woods, where she’s shocked to discover a man she knows.