The Secret of the Imperial Crown

An American journalist appears in Moscow, saying that she is the heiress of the Russian prince.
Her great-grandfather, Prince Medele Glebov, allegedly was a trustee of the last Russian emperor. And on his order, he took out of the revolutionary Petrograd part of the treasure of the crown.
"Diamonds, Faberge Eggs, Crowns and Tiaratices of Russian Emperors, Increased Gold Frames, Pearl, Ruby, Sapphire and Diamond Necklaces Hidden in the Seven Coffins in the pit 7x10 feet in the middle of Mongolian deserts".
Direct searches in the Gobi results did not give. And here the heir arrives in the Russian capital with the original will of the will of the prince. She argues that on behalf of the emperor, 10 cipher keys hidden in the historical sights of Moscow and St. Petersburg were compiled.
An American appeals for help in government agencies, and it is allocated for three employees of the special division of the FSB.
But besides the official "heirs" in search of treasures, there are still some third forces - gangsters, thirsting to get a huge wealth.
In the process of searching, the FSB staff will have to find out who is good who is bad, who is a real heir, and who pretend to them. They also have to be protected from bandits, escape from underground traps left by the ancient builders of Moscow, and meet real love. Well, find the treasure, of course.
But at the last moment, already holding the treasures found in their hands, our heroes will face a surprise