Dublin Murders

Rob, unmoored by Cassie's absence, is increasingly obsessed with Jonathan Devlin, convinced he and his childhood friend Cathal Mills may be dangerous paedophiles. He is desperate to find the one witness to the events in the woods in 1985 that he hasn't yet spoken to - itinerate ex-friend of Jonathan and Cathal's, Shane Waters. But Shane, a homeless drug addict, hasn't been seen since Katy's body was found.

Meanwhile, Jonathan has sent his daughters Rosalind and Jessica away from Dublin. Rob tracks Rosalind down to a dingy caravan park. Soon the extent of Rosalind's disturbed behaviour emerges, and Rob feels he can save the girl. Meanwhile, Cassie starts to back away from Operation Vestal, spending time with Frank as he schools her in the art of being Lexie.

Rob realizes time is running out on the investigation and decides the only way to fully remember what happened that day is to spend the night alone in the woods, totally immersed in that strange world...

Undercover as Lexie, Cassie finds herself emotionally seduced by the house and Lexie's devoted friends. She and Frank discover the locals in the village hate Whitethorn House and its owners because of what they represent - colonialism and cruelty, with the scars and skeletons of the famine cottages. Furthermore, the inhabitants of Whitethorn House are refusing to sell, blocking plans for a new motorway that would bring jobs to the area.

Meanwhile, Rob is obsessed and distressed by his memories of the day of the disappearances. The only thing he can do is to reach out to Sandra, the rape victim who still lives on the estate. But Sandra denies everything, throwing him out of her house.

Everything comes to a head as Cassie confronts Lexie's killer and Rob has a breakthrough about Katy's murder.

The finale finds Rob and Cassie forced into a face-to-face reunion. As arrests are made, Rob and Cassie both come to profound realisations.