Cottingley, Yorkshire, 1917: When two young cousins, Frances Griffiths and Elsie Wright, announce they have photographed fairies at the bottom of the garden, their parents are astonished. But when the great novelist, Sir Arthur Conan Doyle, endorses the photographs' authenticity, the girls become a sensation; their discovery offering something to believe in amid a world ravaged by war.
One hundred years later: When Olivia Kavanagh finds an old manuscript and a photograph in her late grandfather's bookshop it sparks a fascination with the story of the two young girls who mystified the world. Delving deeper into the past, and the truth behind an innocent game that became a national obsession, Olivia begins to question her own beliefs. And as she begins to understand why a nation once believed in fairies, will Olivia find a way to believe in herself?