The wealth of the representatives of the Yusupov family amazed even the members of the imperial family. However, having emigrated from revolutionary Russia, the most famous of the Yusupovs, Felix Feliksovich, was able to take abroad only a small fraction of the jewelry and art that his family owned. The main part of the innumerable treasures was safely hidden ... Nowadays, a part of an encrypted note addressed by Prince Yusupov to an unknown person, which refers to some valuable thing, falls into the hands of the St. Petersburg housewife Nadezhda Lebedeva. A lover of all sorts of riddles, Nadezhda Nikolaevna considered it a matter of honor to restore the missing part of the mysterious note and, possibly, find the hiding place of the Yusupov princes.