Nancy and Calder are moving from London to an isolated slate island, off the west coast of Scotland. But, for Nancy, the fresh start is undermined by the stark surroundings, mysterious locals and the discovery of Calder's dark past. Then one of Nancy's nightmares plays out in real life: Calder's boat upturned in the bay, his body adrift in the icy water.

Miraculously, the doctors manage to bring him back to life, but Nancy doesn't recognize the man who has been snatched back from death's door. As secrets, lies and bodies begin to wash up on the island, Nancy must come to terms with the fact that sometimes the slate cannot be wiped clean.