Ffion follows his instinct back to the bunkers. The real murderer is caught, but still no sign of Helen. Rick follows his intuition about Helen, with devastating consequences.

Ffion and Rick's relationship intensifies as the past continues to haunt the present. Ffion, riddled with guilt and shame, is worried that Abbi's killer remains at large.

In the wake of the incident with the gun, the team links Mel to Harvey's historic murders. Progress is made but Ffion is convinced the killer of all three nurses may still be out there.

A person with a gun has found his way into the local Comprehensive School, looking for Rick's daughter, Mati. Rick, visibly shaken by the day's events, turns to Ffion, rekindling an old flame.

Anna's claims about the past upset Ffion, as the hunt for Ryan Moss - Abbi's ex-boyfriend - intensifies. A chase ends with an arrest - but is the real killer still out there?

The murder of a nurse sends shockwaves through a small-town community.