A friendly group of children spends their summers in an old dacha village year after year. The kids have their own headquarters hidden from prying eyes in a corn field and a legend that says that a treasure trove of treasures of a princess who fled from Napoleon is hidden not far from the village. When a new girl Katya comes to the village with her mother, she becomes a bone of contention for best friends Sonya and Dasha. But it is not only friendship that will have to endure a test of strength. A certain businessman is going to buy a field with a hut and organize a construction market in its place. The children decide not to allow this to happen at any cost and after failed negotiations, they move on to active actions.