Based on Josephine Hart's novel of the same name, the series focuses on a dangerous love triangle. The elusive Anna Barton is engaged to Martyn, but she has started a passionate secret affair with her fiancé's politician father, William. Anna tries to maintain both relationships, while William is caught in a vortex that he can't let go of, and his wife Ingrid knows nothing about it. But how long can this secret be kept secret before someone gets hurt?