Keston Hall, Buckinghamshire, is the seat of the Lydiard family and the imposing setting for a compelling love story that begins in 1907. Beautiful and spirited, Grace Merrill seems to stand with the world at her feet. But then, quite unexpectedly, a family tragedy obliges Grace to abandon her artistic talents and enter a life in service at the Hall. In this Upstairs Downstairs world of sadistic housekeepers and drunken butlers, there is genuine hardship and drudgery for those employed in servicing the few. But Grace soon discovers that she has another talent when, through the merest chance, she manages to escape from the kitchen to the nursery floor. Here she learns to love Lady Lydiard's children as her own. Here, too, she learns her first lesson as a woman, that passion and sacrifice make awkward bedfellows. But if the love of her life, Brake Merrowby, brings her more sorrow than joy, her love for the children more than compensates for her enforced isolation in their world of muffins and rocking horses. As change reaches out to touch the great house, the realities of war leave their mark on the family. Yet for the children, grown and growing, when they stop to look back at the top-floor window they see only their nanny. Almost as if part of the fabric of the building, Grace grows to become not just the touchstone of their lives but in essence the mistress of the house itself.