End of the 19th century. Northern provincial town. Under mysterious circumstances, a very important person disappears. To investigate this unusual case, General Vissarion leaves the capital by ship. At the same time, the carts of the Italian circus “Mario and Jesi” and the young naturalist Dunas in a hot air balloon are rushing to the scene. Soon they will all arrive in this mysterious town and become the heroes of not a simple, but a detective story.