Three years after they narrowly escaped the IRA's worst punishment for informing, Northern Irish sisters Tessa and Marian Daly have built a new life in Dublin with their young children. It's a small island, though, and just as quickly as they disappeared, figures from their past surface to drag them back into the conflict. Tessa is told she must track down her old handler from MI5, Eamonn, and attempt to turn him into an IRA informant, or lose everything. Tessa's reunion with Eamonn revives a host of feelings she has long attempted to bury. As their relationship intensifies and the pressure mounts, long-held secrets rise to the surface, and Tessa must navigate a treacherous landscape of shifting loyalties, all while trying to protect her beloved son.

A producer at the BBC and mother to a new baby, Tessa is at work in Belfast one day when the news of another raid comes on the air. Bomb threats, security checkpoints and helicopters floating ominously over the city have become features of everyday life. As the news reporter requests the public's help in locating those responsible for the robbery, security footage reveals Tessa's sister, Marian, pulling a black ski mask over her face. The police believe Marian has joined the IRA, but Tessa is convinced she must have been abducted or coerced. When the truth about Marian comes to light, Tessa is faced with impossible choices that will test the limits of her ideals, the bonds of her family, her notions of right and wrong, and her identity as a sister and a mother.

Nearly 30 years ago, while Claire and her brother slept upstairs, a brutal crime was committed in their grand London home. The next morning, her father's car was found abandoned, with bloodstains on the front seat. The first lord accused of murder in more than a century, he has been missing ever since. Now a doctor living under an assumed name, Claire learns the police may have found him, and her carefully calibrated existence begins to fracture. She starts to infiltrate his privileged inner circle, who have never broken their silence about what happened that night. Soon, Claire will learn how far she'll go to finally find the truth.

When Nora takes the train from London to visit her sister in the countryside, she expects to find her waiting at the station, or at home cooking dinner. But when she walks into Rachel’s familiar house, what she finds is entirely different: Her sister has been the victim of a brutal murder. Stunned and adrift, Nora finds she can’t return to her former life. An unsolved assault in the past has shaken her faith in the police, and she can’t trust them to find her sister’s killer. Haunted by the murder and the secrets that surround it, Nora is under the harrow: distressed and in danger. As Nora’s fear turns to obsession, she becomes as unrecognizable as the sister her investigation uncovers.