In her twenties, Belle da Costa Greene is hired by J. Pierpont Morgan to curate a collection of rare manuscripts, books, and artwork for his newly built Morgan Library. Belle becomes a fixture on the New York society scene and one of the most powerful people in the art and book world, known for her impeccable taste and shrewd negotiating for critical works as she helps build a world-class collection. But Belle has a secret, one she must protect at all costs.