Winter 1917. As the First World War enters its most brutal phase, back home in England, everyone is seeking answers to the darkness that has seeped into their lives. At Blackwater Abbey, on an island off the Devon coast, Lord Highmount has arranged a spiritualist gathering to contact his two sons who were lost in the conflict. But as his guests begin to arrive, it gradually becomes clear that each has something they would rather keep hidden. Then, when a storm descends on the island, the guests find themselves trapped. Soon one of their number will die. For Blackwater Abbey is haunted in more ways than one…

January 1921. Though the Great War is over, in Ireland a new civil war is raging. The once-grand Kilcolgan House, a crumbling bastion shrouded in sea mist, lies half empty and filled with ghosts, both real and imagined, while it shelters the surviving members of the Prendeville family. Then, when an IRA ambush goes terribly wrong, Maud Prendeville, Lord Kilcolgan’s eldest daughter, is killed, leaving the family reeling. Yet the IRA column behind the attack insists they left her alive, that someone else must be responsible for her terrible fate. Captain Tom Harkin, an IRA intelligence officer and Maud’s former fiance, is sent to investigate. He becomes an unwelcome guest in this strange, gloomy household. Working undercover, Harkin must delve into the house’s secrets–and discover where, in this fractured, embattled town, allegiances truly lie. But Harkin too is haunted by the ghosts of the past and by his terrible experiences on the battlefields. Can he find the truth about Maud’s death before the past–and his strange, unnerving surroundings–overwhelm him?