Finally leaving service as lady's maid to the Mitford sisters, Louisa Cannon sees her wedding day cut short when her new husband DS Guy Sullivan is tasked to quell a potential riot by British fascist Oswald Mosley. But in this fourth outing (after The Mitford Scandal), Louisa is approached by an enigmatic agent who demands she resume her duties as a maid to spy on Unity and Diana Mitford, and she soon finds herself caught between a love lost, a family divided, and a nation in turmoil.