Klaus Rader's rise began when the Wall fell.

He was 26 years old and managing a McDonald's in the sleepy West German town of Hof when the Berlin Wall was toppled 20 years ago on Monday. The next day, East Germans poured into the West. The first stop for many was Mr. Rader's Golden Arches, a siren of capitalism's long-forbidden fruits.

"We were overrun," Mr. Rader recalls. In just hours, all his hamburgers and fries were devoured. What piles of gold awaited the owner of the first McDonald's in eastern Germany, he wondered.

Now 46, Mr. Rader drives a Porsche and is a partner in an international chain of hip Italian eateries sprouting in Warsaw, London, Istanbul, Budapest, Washington and even in Berlin's Potsdamer Platz, near where the Wall once stood.

"It all started in that McDonald's" the night the border opened, Mr. Rader says...