Gosh, just one book?
The Poisonwood Bible, Prodigal Summer both by Barbara Kingsolver.
The Handmaid's Tale the Maddadam Trilogy all by Margaret Atwood.
Birdsong Sebastian Faulks.
I can't choose between the Allende books.
1984 Orwell
Michael Pollan The Botany of Desire
Snow Flower and the Secret Fan by Lisa See.
What I loved by Siri Hustvedt
Julian Barnes: Arthur and George
Curtis Sittingfeld American Wife
Sarah Waters books.
Paula McClain The Paris Wife
Elizabeth Gilbert The Signature of All Things
And my new discovery? Ann Patchett. Loved, loved loved Bel Canto