KONOPISTE CASTLE, Czech Republic — When a young Serb named Gavrilo Princip stepped forward on a Sarajevo street and fired a pistol at a middle-aged couple 93 years ago, he sent history stumbling down an unexpected new path.

The couple, of course, was Franz Ferdinand, archduke of Austria-Este, heir to the Austro-Hungarian Empire, and his wife, Sophie. They were killed. The world went to war. Millions of people died and the political map of Europe was redrawn.

Now, Franz Ferdinand’s great-granddaughter, Her Serene Highness Princess Sophie von Hohenberg (or Sophie de Potesta to her neighbors), is trying to right what she sees as one of the wrongs from those years. She hopes to get Franz Ferdinand’s castle back in the bargain.

The 1919 Treaty of Saint-Germain-en-Laye carved up the old Hapsburg empire into new states: Austria, Hungary, Czechoslovakia, Yugoslavia and parts of Poland. The Hapsburg family, which had ruled that part of Europe for more than 600 years, was stripped of its properties and titles. Franz Ferdinand’s children had already been turned out of their parents’ beloved home, Konopiste Castle, in the empire’s province of Bohemia, now the Czech Republic. It was taken by the state.