The bluebird flew out of the breeder's cage. But what is he going to do with us? After all, he comes from completely different regions! Fortunately, he is taken in by the birds from the bird tree, who live there as one big family under the watchful eye of the old parrot. During the summer, Modroušek will experience many big and small adventures with them, both happy and dangerous. And children will learn interesting details about building bird nests, hunting for caterpillars and what happens when a cuckoo chick hatches in one of the nests of unsuspecting bird parents. As autumn approaches, however, colder weather will arrive and Blueberry will fall ill. Bird friends take care of him selflessly. Will it be possible to save the fragile bird?