Daphne by Justine Picardie

It's 1957, and Daphne is having trouble in her own marriage — her husband has had an affair, and then a breakdown. Meanwhile, Daphne is trying to research a book about Branwell, the Brontë sisters' mysterious brother. Justine Picardie gets us into this world with great skill — and then jumps right into the present-day life of a young woman, who is herself researching Daphne du Maurier's work on Branwell. Naturally, this woman is also in a troubled marriage, and as we skip between past and present, the intrigues all deepen, and reflect each other; it's well-designed, and very absorbing..

Synopsis by Foyles.co.uk

It is 1957. The author Daphne du Maurier, beautiful, famous, despairing as her marriage falls apart, finds herself haunted by Rebecca, the heroine of her most famous novel, written twenty years earlier. Resolving to write herself out of her misery, Daphne becomes passionately interested in Branwell Bronte, the reprobate brother of the Bronte sisters, and begins a correspondence with Alex Symington, an enigmatic Bronte scholar and bibliophile, as she researches a biography. But behind Symington's respectable scholarly surface is a slippery character with much to hide, and Daphne becomes embroiled in a literary mystery where truth and fiction become indistinguishable. The last untold Bronte story, Daphne is a story of obsession and possession; of stolen manuscripts and forged signatures; of love lost, and love found.