Island - Jane Rogers

The island is a place where things are not quite as they appear; a magical place where the murder of a reclusive woman is not a cut and dried case.
'I thought I had come to the island to wrest control of my life back from the woman who had sabotaged it. But I was wrong. My mother was still writing my plot.'
Nikki Black, intent on punishing the mother who abandoned her at birth, goes to the island with only one aim in mind: revenge. But her plans are confounded by the discovery that she has a brother. Not just any brother but a brother strangely possessed by their mother; a brother with a terrifying violent streak; an apparent simpleton whose head is filled with the stories of past islanders, Crofters, Vikings, Little People. A brother whose dangerous love and strange way of seeing the world transform Nikki's life.