In the biggest country in the world lives a small scientist—Egorka, a first-grader. During his holidays with his grandmother in the village, he meets a little dragon, Zmey Dobrynnych, and together with his older brother helps him get to the Mountain Dragon. On the way, Egorka lands in different stories, meets new friends, and, most importantly, understands that the most important things in the world are friendship, love, and kindness.