A group of old university friends are in Unst, Shetland's most northerly island, to celebrate the wedding of one of their friends to a Shetlander. But late on the night of the wedding party one of them, Eleanor, disappears - apparently into thin air. It's mid-summer, a time of light nights and unexpected mists. The next day Eleanor's best friend Polly receives an email from her saying she'll never be found alive. And so it seems, because the woman's body is found, lying in a small loch close to the cliff edge.