The cat is unimportant. Litvinova A.V., Litvinov S.V.

long ago, the great master Leonardo da Vinci worked on a unique invention, which he could not bring to perfection... Nowadays, the great computer, Anton developed his idea and created a computer program worth millions of dollars... Katin's nephew Lenchik came running to the aunt after help: his friend disappeared. Before disappearing, Anton hid his program somewhere on the Internet. And the ways were sent to the addresses of the lady who married foreigners through the marriage bureau where he worked.

Aunt and nephew go to Europe, and it turns out that they have very dangerous competitors. The cascade of chasing and adventure non-stoply carries Katya and Lenchik through the Venetian canals, the narrow streets of Verona, Madrida Avenues, the snowy mountains of the Sierra Nevada... further and further-in search of a miracle...