The Mitford Affair is a historical novel by Marie Benedict published in 2023. The novel is set in 1930s and 1940s Europe, tracing the ascendancy of Adolf Hitler’s Nazi Germany through the family dynamics and love affairs of the famous real-life Mitford sisters. The Mitford Affair explores the nature of political and social power, exposed through a focus on a historical family drama in which generational conflict reflected—and influenced— the wider national and international crisis of World War II.

Marie Benedict has written eight historical novels which focus on women and their impact on history. Her novels are “historical” fiction in the sense that they are set in the past, but they also focus on real historical events and people. The Mitford Affair is a combination of historical fact and narrative invention. Other works by Marie Benedict include The Only Woman in the Room, Lady Clementine, and The Personal Librarian.

This guide is based on the Sourcebooks 2023 edition of The Mitford Affair.

Content Warning: The source material and this guide include descriptions and discussions of fascism, personal and political violence, racial discrimination, antisemitism, war, trauma, incarceration, alcohol misuse, suicide ideation, death by suicide, and grief. 

Plot Summary

Set in 1930s Britain and Germany, The Mitford Affair concentrates on three of the four eldest Mitford sisters. These adult Mitford sisters are society figures: well-connected, affluent, and noted for their beauty and intelligence. When the novel opens, in 1932, Nancy, the oldest at 28, is a published novelist and hopes to combine her career with a future marriage and family life. Pamela, aged 25, is also unmarried and prefers a quiet country life to London society. Diana is the sister most noted for her beauty. Aged 22, she is married to the wealthy writer and aristocrat Bryan Guinness. They have two children and maintain a luxurious society lifestyle. The fourth sister, Unity, is entering the London social scene aged 18 although she finds this environment awkward and anxiety-inducing. The family also includes two younger sisters, Jessica “Decca” (aged 15) and Deborah “Debo” (aged 12), and one son, the 23-year-old Tom.

The lives of the whole family change when Diana falls in love with Sir Oswald Mosley, the founder of the British Union of Fascists. Diana becomes increasingly engrossed in fascism, divorces her husband in 1933 (a shocking scandal at the time), and commits her life to both pushing forward fascism and Mosley’s career.

As Diana becomes committed to fascism, she brings Unity along with her. Unity becomes deeply attracted to fascism because of the order it creates; both Unity and Diana feel they have found a purpose. Unity becomes infatuated with Adolf Hitler, then the pro-fascist Chancellor of Germany. Diana and Unity form connections in fascist society, making several trips to Germany to watch Hitler speak and meet other like-minded people. Unity becomes so invested in this life that she moves to Germany to learn the language and be closer to Hitler. A major moment for her occurs when Hitler notices her at a restaurant and asks about her. Meanwhile, Nancy and much of the Mitford family are worried about Unity and Diana. Support—let alone idolization—of Germany is a problem for Nancy’s father, who fought against the Germans in World War I.

Nancy marries Peter Rodd in 1933. She loves him but struggles when he turns out to have an alcohol addiction and is increasingly unemployable and financially unstable. He is also unfaithful to her. Nancy stays, determined to have children. She starts writing a new novel partly for income but also because she aims to satirize Mosley and the fascist ideologies that her sisters have fallen for. When Nancy publishes her new novel satirizing Mosley, Unity, and fascism, this creates conflict within her family. Nancy and Peter go away together for a month and reconnect. When they return from their trip, Peter stops drinking and is more faithful to Nancy. Nancy worries about her lack of pregnancy as she and Peter have been trying for a baby since their marriage. Nancy is approached by Winston Churchill, a family friend, who asks her to help him deal with the social and political turmoil Diana and Unity are causing.

Unity has become close friends with Hitler. As part of his inner circle, she has been given a new luxury apartment in Munich and front row seats at the Olympics. Hitler is often hidden away, planning and working, and, in his absence, Unity is distraught. She has become so obsessed with Hitler that any distance between them is completely destructive to her happiness. Her family has tried to intervene in her new life, but they distance themselves further when she publishes antisemitic opinions in a newspaper. Unity is fully invested in fascism, Nazism, and anything Hitler believes in.

Meanwhile, Mosley’s wife dies (1933), and Diana increases her pursuit of him. They have been lovers since 1932 but he has conducted numerous affairs while married, including with his sister-in-law. Diana knows that if she can advance Mosley’s career, she can be his only lover. She is so dedicated to Mosley that, after a car accident requiring two facial surgeries, she discharges herself from the hospital to follow Mosley to Italy. Unity helps Diana connect Mosley with Hitler. Unity convinces Hitler to host a lunch for Mosley, a major turning-point in Mosley’s fascist career. Mosley meets German fascists who will fund Mosley’s political organization the British Union of Fascists, provided he will openly criticize and disenfranchise the Jewish community in Britain. Mosley and Diana marry in a secret wedding organized by Hitler in Germany in 1936.

Diana is devoted to Mosley, but she is concerned that he is not a strong enough leader to fulfill Hitler’s expectations and model. She creates a proposal in which Nazi Germany will fund German radio stations that will broadcast in Britain; this will support a business venture of Mosley’s. Diana is desperate to make this a success because Mosley’s fascist organization is losing money and support in Britain.

Unity is invited to the official annexation of Austria by Nazi Germany (the Anschluss, in 1938). She is photographed with Hitler and reports home that Austrians are thrilled to be part of Germany again. Her father, a British peer, makes a speech in Parliament supporting Hitler and the Anschluss, highlighting that Unity has introduced her parents to Hitler and that they support a policy of appeasement toward Germany’s fascist government.

Nancy makes notes of Unity and Diana’s trips to Germany and anything they say about Germany or Hitler. She plans to share these entries with Winston Churchill but doesn’t think her notes are very significant. On a visit to England, however, Unity lashes out at Nancy and reveals secret information about Germany: Hitler plans to invade and annex former Czechoslovakia. Diana has her two sons perform a Hitler Youth song and dance for her family. These two moments reveal to Nancy that her sisters are traitors to Britain.

Nancy goes to France with Peter to help the thousands of refugees coming in from Spain at the end of the Spanish Civil War. This reignites her sense of purpose and reminds her of what’s important in the world. In August 1939, Hitler informs Unity and Diana that they must leave Germany and return to England because peace between their two countries is impossible. Unity is devastated: She breaks down on hearing the news and experiences suicide ideation.

Diana returns to England and continues to work on establishing German radio broadcasts in Britain. The Mitford family worries when they don’t hear from Unity, still in Munich. When Britain officially declares war on Germany in September 1939, Unity attempts to end her life by shooting herself in the head. She does not die but is severely injured.

Nancy becomes a spy for Winston Churchill. She searches through Diana’s study and finds evidence of the German radio broadcast plan, which she passes on to Churchill. Hitler arranges for Unity to be moved to a hospital in Switzerland, where Unity’s mother meets her and brings her back to England. Unity has a life-changing brain injury. Nancy blames Diana for getting Unity involved with Hitler. Diana admits that she had suspected Unity would hurt herself and hadn’t told anyone until it was too late. Nancy is also disgusted by Diana’s treasonous activity against Britain. Churchill reveals that Diana and Mosley have been investigated by MI5 (the British internal security service) since before the war.

Nancy starts writing and publishes a novel called Pigeon Pie, which includes a narrative thread about a plan to start a German radio station in Britain during the war with Germany. Mosley and Diana are arrested and interned under Britain’s wartime defense internment program. Nancy worries about the role she played in separating Diana from her children, but she ultimately decides that her own family guilt is less important than holding Diana accountable for her treasonous acts and her callous disregard for Unity’s safety.