Dasha and Katya are sisters, and, like any sisters, they are alike. But this similarity is only external. The girls' personalities differ like heaven and earth: cheerful, amorous Dasha and quiet, hardworking Katya. But one day everything changes. Dasha suddenly becomes silent and withdrawn, while Katya, on the contrary, blossoms. Having abandoned her textbooks, she now runs around on dates. What happened to the sisters? Why doesn't Dasha talk to Katya anymore? Will the girls be able to figure everything out, because not just one boy is involved in the case, but two at once!