The young Maria Theresia impatiently awaits her reunion with Franz Stephan of Lorraine. She had already fallen in love with the young duke as a child. However, in the absence of a male heir for the House of Habsburg, the courts of Europe are now searching for a more politically important marriage candidate for the young archduchess. This candidate is to rule the Habsburg hereditary lands, since a woman would not be accepted. Crown Prince Friedrich was proposed, because although he is a Protestant, the union between Habsburg and Prussia would secure peace for Austria. When the Prussian delegation arrives in Vienna, Maria Theresia makes no attempt to hide her negative opinion about the Prussian court. In doing so, she made herself seem ridiculous throughout Europe as a candidate for marriage, so her confessor suggested that she enter a convent and clear the way for her sister Anna. Through her teacher, Spannagel, Maria secretly learns about the Pragmatic Sanction, thanks to which a woman can also ascend to the Habsburg throne. However, the Hungarian Count Esterhazy discovers this and betrays her. In front of the court, she explains to Karl how she can marry Franz Stephen without the marriage endangering the European power structure. France would recognize the Pragmatic Sanction if Franz Stephan ceded Lorraine to France upon her marriage and received Tuscany in compensation. Impressed by Maria Theresia's determination, Karl relents. But Franz Stephan resolutely rejects the renunciation of Lorraine, which makes Maria Theresia doubt Franz Stephan's love. Meanwhile, Grumbkow plays a double game: he warns the terminally ill Prince Eugen of an impending war with Prussia, but at the same time he assures Maria Theresia of the European rulers' support for the Pragmatic Sanction. Above all, he claims that Prince Eugen has been bribed to enforce Maria Theresia's marriage to Friedrich of Prussia. Maria Theresia wants to confront Prince Eugen, but he is already dying and can only advise her to seek advice from Prince Kinský. On Maria Theresia's mother's birthday, Franz Stephan confesses his love for Maria Theresia before the assembled court, and accepts all the conditions for marriage. Their wedding is celebrated with great grandeur, but the strict court ceremonial leaves the young couple little room to live out their love. To Karls' disappointment, his first two grandchildren are girls. The entire court, as well as the population of Vienna, fears that fate will repeat itself and that Maria Theresia will be denied a male heir to the throne. To escape the pressure of the court, the young family move to Tuscany. While Maria Theresia enjoyed her family's happiness, Franz Stephan promoted the cloth manufacturers. Their carefree days are numbered, however, when Count Kinský brings them the news of Karls' death.

The affairs of the state take over Maria Theresia’s time. The ministers warn Maria Theresia about her enemies, and especially about the Prussian envoy, Grumbkow. However, the latter wins Maria Theresa's sympathy. When Kinský urges her to ally with the Hungarians against Prussia, Maria Theresia refuses because of her deep-seated resentment against Count Esterhazy. While Maria Theresia struggles to gain the respect of the ministers under the growing threat of war, Franz Stephan wants to establish textile manufactories in Vienna. In order to convince the ladies of the court about the advantages of silk, he did not shy away from lewdness and thus weakened Maria Theresia's position. Things continued to go downhill for Maria Theresia. Grumbkow, who had been executed in Prussia in the meantime, was exposed as a double spy, Prussia invaded Silesia, the army was in a desolate state, and the nobility turned their backs on the Viennese court. In addition to this, Maria Theresia's youngest daughter Karolina falls ill with smallpox and her marriage is in deep crisis. On the advice of her mother, Maria Theresa makes Elisa Fritz her ally and arranges for a magnificent ball to be held. Her plan works. The nobility return to court, she wins back Franz Stephan as her husband, and Kinský becomes her advisor. Meanwhile, little Karolina dies. Soon after, Vienna celebrates the birth of an heir to the throne, but the Prussians advance threateningly. Bavaria, France, and Spain have also declared war on the Habsburgs. In the war, Maria Theresia's men succumb to their overpowering adversary. Maria Theresia is dependent on the help of Hungary and turns to Esterhazy. The visit of the dashing count and his entourage throws the ladies of the court into turmoil. Franz Stephan jealously observes his wife's efforts to flatter Esterhazy. When he invites her to start a new life in Hungary at his side, she accepts his offer as a pretense. At the masked ball, the court lady Colloredo, whose interest is Franz Stephan's, wears an identical dress to Maria Theresia. The ball party turns away from her, but Esterhazy slips her a note for Maria Theresia, who he is expecting in a boudoir. Maria Theresia accepts his invitation, but finds only a note stating that he would never accept a woman giving herself to him out of superior interest. Esterhazy approaches Maria Theresia, who is standing alone on a balcony, but mistakes her for Colloredo and confesses to having lost this game. Maria Theresia has no choice but to ask the Hungarians for help. Together with Franz Stephan, she embarks on a journey to the Hungarian Diet in Pressburg, where she wins the support of the Hungarian nobility in an emotional speech: under Esterhazy's leadership, tens of thousands of Hungarians will go to war for Maria Theresia. Maria Theresia returns to Vienna as Queen of Hungary. However, she is much more interested in the strengthened love between her and Franz Stephan.

Maria Theresia still has to wage war. Since she succeeded her father as ruler, her enemies have been attacking her lands or laying claim to parts of her empire for themselves. Even though there is a truce between Austria and Prussia, Prussia presses France to intervene in the war. And although Ludwig XV hesitates, Mlle de Chartres, Maria Theresia's mother-in-law, is ordered by Marschalls de Belle-Isle to spy on the Viennese court. Meanwhile, Maria Theresia's husband Franz Stephan is going about his own business in a palace on Wallnerstrasse. He even traded with Austria's enemies in goods that were important for the war effort. However, he concealed from his wife the exact source of the profits that filled Maria Theresia's war chest. Franz Stephan's mistresses, whose generous patron he is, also go in and out of Wallnerstrasse. At the Hofburg, the visit of Mlle de Chartes is met with only limited enthusiasm. Above all, Elisabeth, Maria Theresia's mother, is skeptical of the Frenchwoman. However, Maria Theresia's brother-in-law Karl of Lorraine and her sister Anna seem to take a liking to each other. It is not long before the French army is able to make great land gains thanks to Mlle de Chartres' treachery. Although Maria Theresia sees through her mother-in-law's doings, the rules of the court do not allow her to impose sanctions, especially since she gains a capable officer for her army in Karl of Lorraine. At the same time, news of illegal gambling outraged Maria Theresia. When a count ruins himself financially and commits suicide, she wants to hold his creditor, Baron von der Trenck, responsible, but Maria Theresia's waning fortunes in the war play into the latter's cards: to stop the French, she pardons the ill-famed Trenck and has him raise a Hungarian regiment. In order to fill his wife's war chest, Franz Stephan intensifies his dealings with the Habsburgs' enemies, but his luck does not change yet: Maria Theresia's empire is in serious danger when the French conquer Prague. At the same time, her mother-in-law leaves no stone unturned to weaken her prestige. In this tense situation, her former tutor Tarouca is Maria Theresia's most important confidant. Weeks after the wedding of Anna and Karl, the courtiers are still celebrating when Maria Theresia receives the redeeming news: Trenck is victorious in Bavaria. Mlle de Chartres, who had failed as a spy for Ludwig XV, returns to her country estate. But all is not well with Maria Theresia's marriage to Franz Stephan. And it gets worse: news of Trenck's war crimes reach her.

Although Count Trenck's accusers are not free of self-interest, as Maria Theresia can no longer ignore the count's war crimes and has him thrown into prison. She is much worse off, however, when Franz Stephan makes a mockery of her at her own court. She sets up a chastity commission with her confessor Father Johannes at its head. With an iron hand, the Jesuit takes action and, on the advice of the papal nuncio, also takes aim at the goings-on in Wallnerstrasse. He drew up a long list of Franz Stephan's mistresses, who was also the grand master of a Masonic lodge. Maria Theresia not only banished the governess of her children, Countess Fuchs, from court because of her affair with Count Tarouca, but she also publicly exposed Franz Stephan's mistress Sophie. For Franz Stephan, she has thus crossed a red line: he moves into his own chambers, and their marriage exists only on paper. When the weaknesses of the army become apparent during a visit to the troops in Olmütz, Maria Theresia proves herself open to reform and makes the free spirit Van Swieten her personal physician. Above all, in a time of uncertainties, she allows herself a moment of weakness and seduces the young officer Hádik. The events of Olomouc have transformed Maria Theresia: She retrieves Countess Fuchs, but above all she feels guilty about Father Johannes' actions towards the Viennese Freemasons: in order to save them from the death penalty, Franz Stephan had to finance their escape. Maria Theresia's moment of weakness has consequences however, as she is pregnant. But unlike her sister Anna, who is expecting her first child, Maria Theresia cannot rejoice and takes Anna into her confidence. The latter does not withstand Father Johannes' threats in confession and reveals the secret to him. Having put Maria Theresia's reign in danger, the frightened Anna is sent back to her new home in Brussels. At the same time, other posts are intended to appease Father Johannes, but when Anna's daughter is stillborn and Anna also dies, Maria Theresia is no longer willing to put up with Father Johannes' self-righteousness and relieves him of his offices. The prospect of his farewell sermon makes Maria Theresia fear the worst, but instead of him, the papal nuncio preaches, making Maria Theresia a role model. Father Johannes, on the other hand, will from now on be only a simple monastic brother. The Holy See also forgave Franz Stephen thanks to his generous donations. Harmony reigns again between Maria Theresia and Franz Stephen, who regards her newborn daughter as his own child.

Der letzte Teil der opulenten TV-Serie über die Regentin Maria Theresia! Neben der großen Politik gilt Maria Theresias Interesse ihren Kindern, für die sie Ehepartner an allen europäischen Fürstenhöfen sucht, um mit starken Allianzen einen dauerhaften Frieden zu sichern. Ihr Hauptaugenmerk gilt ihrer jüngsten Tochter Maria Antonia, die sie mit dem französischen Dauphin verheiraten will.