If I didn't spy, I'd be in the dark eternally. I live in a maze of unknowing -- Maisie's maze -- and I hate it. I need to be informed . . .'

The summer of 1967, at a decaying house in the heart of Suffolk: an artist is painting a portrait of thirteen-year-old Maisie and her elder sisters, beautiful Julia and bookish Finn. Maisie embarks on a portrait of her own: she begins an account of her family and of her village friend Daniel Nunn, a young man she idolises, whom she watches over the chasm of a class divide. But is Maisie's description of a summer idyll all it seems? This is the summer when the three sisters' lives will irrevocably, and terribly, change.

The winter of 1991, in London: the now-famous portrait of the three sisters features in a major retrospective. Daniel Nunn, haunted by the vanished England of his childhood, obsessed by the three sisters and newly determined to understand what happened that last summer, pursues the ghosts of his past.