The story about Alexander I Karađorđević, “The Unifier”, begins with his return from World War I to the liberated Belgrade, in November 1918.

At the age of 24, Alexander Karađorđević has taken over the royal duties from his ailing father Petar Karađorđević, successfully commanded the army in two Balkan Wars, and impressed his allies with victories in WWI. The Regent, tired of the six-year warfare, undertakes to create Yugoslavia, a country dreamed of by the South Slavs in the 19^th century.

After proclaiming the Kingdom of Serbs, Croats and Slovenes, he is faced with strong opposition both from his allies and the Serb nationalists, who demand the creation of Greater Serbia instead of Yugoslavia. In the coming years, the problems continue to multiply.

After the death of his father, King Peter, Alexander becomes king. A loner, who spent his youth waging wars, marries a lovable, noble and beautiful Romanian princess Maria, who gives birth to his three sons in the years to come. Finally, good things are happening in his life. However, his country is threatened from many sides. He is forced to impose dictatorship. Amazingly, under conditions of dictatorship, the country is visibly progressing, despite the fact that those are the years of a major global crisis. That is also the time when the Monument of Gratitude to France is unveiled at Kalemegdan.

In 1934, Alexander is invited to visit France, so that the country could pay tribute to its wartime ally. This turns out to be his last journey, as he is shot to death in Marseilles.