The Good Neighbours, by Nina Allan

This is an odd mix of a murder mystery with elements of a fairy novel. Cath is photographer who works in a Glasgow record shop, but she returns to the island where she grew up, intending to photograph murder houses. One of these is the house where her best friend was murdered when both girls were in their teens. Killed at the same time were the mother and the younger brother, followed quickly thereafter by the death of the father (the presumed murderer) in a car accident. Twenty years later Cath wants to understand the murders, and her amateur investigation leads her haphazardly to new friends and new theories. One of the theories involves the fairies, or the "good neighbours" as they are sometimes called.  Cath's leaps of intuition seem followed by discoveries that lead her further, but the internal logic of the narrative is flawed. And the ending (like the ending in Allan's earlier novel The Rift) is very unsatisfying. The dust-wrapper blurb describes the book as "an enquiry into the unknowability of the past and our attempts to make events fit our need to interpret them"--which seems a highfalutin way of saying that the book is about misdirection and failure. Certainly the author means this, but the author writes well enough to keep the reader going, even as one realizes the frustrating direction that the tale is following.