Grace Chapman has an enviable set-up, living comfortably with her husband, bestselling author Ted, in a picture-perfect farmhouse on the Hudson River in New York state. Then Ted advertises for a new assistant, and Beth walks into their lives. Organised, passionate and eager to learn, Beth quickly makes herself indispensable to Ted and his family. But Grace soon begins to feel sidelined in her home - and her marriage - by his ambitious younger woman. Is Grace just paranoid, as her husband tells her, or is there more to Beth than there first appears?