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The third book in the series about the adventures of the boy Yaroslav.

A serious failure in the interworld coordinate system led to the formation of a mysterious Portal at the intersection of the glorious rivers Dnipro and Tisoria, in which the inhabitants of Kyiv and Lumbernais began to disappear unwittingly. To eliminate the cause of the malfunction, it is necessary to penetrate the mysterious world of the unknown DniproLand and restore order between the worlds. Only the Knight of the Emerald Order can do this. The new story will not be complete without the favourite of all readers of the series, the cat Wolf-Slavka. And a new bird heroine will appear.

So, the adventures continue!