Plot
During World War II, Wehrmacht Captain Brandt takes command of the bodyguard of deposed German Emperor Wilhelm II at Huis Doorn, near Utrecht, the Netherlands. The Germans are concerned that an Allied spy may be planning to assassinate him. While Wilhelm has no power, the SS are aware that he still has great symbolic importance to the German people.
The Kaiser's adjutant Colonel von Ilsemann gives Brandt strict orders not to interfere with the female servants, but Brandt is quickly drawn into impulsive sex with one maid, Mieke de Jong. This develops into a passionate affair. She reveals to Brandt that she is Jewish and after a pause, he replies, "I'm not," telling her not to share her secret with anyone else.
Gestapo Inspector Dietrich informs Brandt that the British Secret Service has an agent with a radio hidden in a nearby village, and orders Brandt to identify a second agent known to be inside the ex-Kaiser's household.
Before a visit from Reichsführer-SS Heinrich Himmler, Brandt notices a smell of gun oil from Mieke's room. He follows Mieke when she visits the village pastor and hears her tell him that she is prepared to assassinate Himmler as revenge for the SS having murdered her father and husband. The pastor responds that assassinating Himmler is not their mission.
The SS pinpoints the pastor’s radio transmissions. They arrest and savagely torture him, demanding the name of the other spy. Shortly afterwards, Wilhelm's ambitious wife Hermine, tells him of Brandt and Mieke's affair. She expects Wilhelm to dismiss Mieke and have Brandt court-martialed, but the ex-Kaiser responds that even though he no longer rules Germany, he will rule his own house. He tells the lovers that he fathered illegitimate children before and after marrying his first wife, Empress Augusta Victoria. Saying he will not be a hypocrite, the Kaiser tells them to be more discreet.
During a house search before Himmler's arrival, Brandt himself searches Mieke's room to protect her cover. Brandt learns that the tortured pastor will soon reveal Mieke's identity and he urges her to flee. She refuses.
Himmler extends to Wilhelm an invitation from Adolf Hitler to return to his former throne in Berlin. He then tells Brandt and Dietrich that the invitation is a bluff, intended to draw out and execute anti-Nazi monarchists in the German resistance. Hermine is overjoyed at the thought of becoming Empress of Germany but Wilhelm, troubled by Himmler's boasts about the euthanasia of disabled children, remains unsure even when von Ilsemann suggests that Wilhelm can become "a restraining influence."
When Brandt asks von Ilsemann whether an officer can serve something other than his country, the Colonel replies, "First you must decide what is your country and if it even still exists." Brandt tells von Ilsemann of Himmler's plans for the Kaiser's supporters.
Mieke delivers to Wilhelm a message from Winston Churchill, offering the Kaiser political asylum and the throne of a defeated Germany after the war. Wilhelm refuses, having decided that he is reconciled to the loss of his throne.
As the Gestapo closes in on Mieke, Brandt devises an escape plan. Wilhelm, Mieke, and Brandt escape in a van as the Kaiser pretends to have a heart attack. In the process, Mieke almost takes a suicide pill. Brandt saves her life and capture by killing Dietrich. Mieke asks Brandt to flee with her, fearing he will be executed for the murders. Brandt insists that he has a duty to Germany and has a good alibi. As Mieke departs, Brandt asks Mieke to marry him. Before fleeing, she accepts and tells him to find her after the war.
Some time later, Brandt is working in Berlin. A package which contains a book of Nietzsche's writings that Mieke had once shown him is delivered. Inside is written a London address. In London, Mieke is seated on a park bench when she is informed that Churchill is ready to see her. Rising, Mieke puts her hand on her stomach; she is pregnant with Brandt's child. In Doorn, Colonel von Ilsemann informs Wilhelm that Brandt has called from Berlin with wonderful news. Realising this means Mieke has escaped to Britain, Wilhelm is overjoyed.
