Annie is the great love of Graham's life. Here they are in late middle-age, the photographer and the bookseller, so mismatched and yet so well-matched. Theirs is a happy marriage of nearly thirty years – and even the happiest of marriages, Graham tells himself, have their secrets.

Then the unthinkable happens, and suddenly Annie is alone, stumbling in the dark. How much can we ever know the people who love us?