A girl with asthma is locked in a “golden cage” in the healing mountains of Crimea. She is very lonely because her teacher is grumpy and boring, and there is no one else around. Books by naturalist writers slightly brighten up loneliness, but do not save us from it. One day the heroine finds herself an unexpected friend - a bush of a strange bluish color. After this, a chain of fantastically humorous events unfolds, as a result of which it turns out that an unusual friend recognizes people and is capable of active actions against enemies. He saves the girl several times, and then the girl saves her potty friend from a vengeful teacher. As a result, the teacher was not only approximately punished, but also partly re-educated, believed in the value of her bush friend, also became interested in botany and began to breed an unusual medicinal plant.