Bestselling author Paula Hawkins set her new book on a fictional tidal island. Here she examines the power and appeal of islands

There is something about an island that stirs the imagination. Or, in any case, it seems to stir mine.

A few years ago, on a trip to the Côte de Granit Rose in Brittany, I walked along seaweed-strewn sands towards one of the many tidal islands dotted along that coastline. As I approached I noticed that on the nearest island, there was a tiny house – a single cottage, all alone – and I felt a familiar prickle running up my spine, the shrinking of the scalp that tells me to pay attention, that there’s something here: the beginning of a story.