Homeless boys Mitka and Petka feed on sausages stolen from the shops by their four-legged friend "Tresor". After watching the circus performance, the children will change the dog's name and call him "Chamberlain" like the circus performer dog. Because of their street adventures, the boys will be placed in an orphanage, where Mitka and Petka will become pioneers. One day, "Chamberlain" saves Mitka from drowning, and the pioneers give him a new name, "Ertgula".