Cambridge student Ophelia Marsh begins an affair with lecturer, Michael Callaghan. After tracking him down to his family home in Ireland, she discovers his wife has died tragically in a house fire and begins to feel haunted, perhaps by more than just guilt.

With Michael called back to Cambridge for a mysterious family emergency, Ophelia is left in Ireland to contend with the disturbing intrusions of Roisin's mother, Mary, and her paranoia begins to take her down a darker path.

As her obsession with Roisin deepens, Ophelia begins to fear that Michael is not telling her everything. Meanwhile, Ruth's investigations in Cambridge reaches Ireland through the arrival of a mysterious stranger.

As the truth about Roisin finally breaks through the web of lies and deceit, Ophelia tries desperately to escape, while the architects of this manipulation attempt to cover their tracks.