The exciting story of a royal necklace stolen by a gang led by Count Cagliostro. As a result of this daring theft, the honor of Queen Marie Antoinette was unfairly disgraced, which led to the French Revolution and the execution of the royal family. This whole story was once described by Dumas the Father, but he primarily recreated the grandiose scam itself. The present novel shows what happened next. And then there was an extremely interesting trial. The leader of the gang, Count Cagliostro, was released, and only Countess de la Motte was imprisoned. From prison, the countess fled to England, and then, according to legend, she ended up in Russia, first in St. Petersburg, and then in Crimea, keeping the last remnants of the great diamond necklace. This Russian trace is recreated in the book.