Sisi, the daughter of the Bavarian Duke Max, grows up carefree and close to nature with her siblings at Lake Starnberg. When the young Austrian Emperor Franz Joseph is to marry her older sister Helene, Sisi reluctantly goes along to Bad Ischl for the engagement. But a fateful encounter between Sisi and Franz suddenly changes the course of events.

Sisi has fallen in love with Franz. Without hesitation, she follows him to Vienna as his future wife. But the strict court ceremonial quickly gets to the freedom-loving Bavarian princess. Out of love for Franz, she is nevertheless prepared to put up with all the hardships and duties. She knows that she must first earn the respect of the court. Sisi finds a friend and confidante in Fanny, whom she smuggles into the palace as a maid under a false name.

The young couple's wedding night does not go as planned and Sisi needs Fanny's advice more than ever. But Countess Esterhazy exposes Fanny as an impostor and banishes her from court. It is only during their honeymoon in Laxenburg that Sisi and Franz slowly find their way to each other. At her first, official reception as empress, Sisi surprises everyone with her excellent knowledge of the Hungarian language and the kindness with which she treats the Hungarian nobility.

Sisi is pregnant. The young imperial couple do not have much time to enjoy their happiness together. The conflicts in Hungary come to a head, and the rest of Europe is also seething. Countess Esterhazy hopes that Sisi can persuade the Emperor to negotiate with the Hungarian nobility. She arranges a secret meeting between Sisi and Count Andrassy. But before she can speak to Franz, an assassination attempt is made on him during the christening of their daughter Sophie.

Franz barely survived the assassination attempt in the church. But when there are uprisings against the Habsburgs in Italy, he goes to war. To help the soldiers as well, Sisi helps out in a military hospital in Laxenburg and cares for the wounded. The mood in Hungary is still heated. Sisi succeeds in persuading Franz to meet Count Andrassy during a reception in Budapest and negotiate a peace treaty. At the height of the festivities, another dangerous incident occurs.

The new assassination attempt on Franz was prevented, but the young imperial couple is struck by a terrible blow of fate in Budapest. The little princess Sophie dies. Sisi falls into deep, immeasurable grief and Franz distances himself from her more and more. Fanny must pay for her crimes. In Europe the signs continue to point to war, Napoleon III claims parts of the Habsburg lands in Italy for himself. Sisi refuses to give up and fights - for herself, her people and her love for Franz!