Twelve-year-old Andrew grows up without a father, he has a complex character. He does not trust adults. His mom can't find a common language with him. It is the fault of Andrew his younger brother, Yuri, who is hit by a car. Jura in serious condition gets to resuscitation, he needs expensive surgery. Mom sends her eldest son to his grandfather's village. Andrew never saw him because his mother quarreled with her father before he was born. Andrew is a city teenager and goes to the village for the first time. He has a biased attitude towards his grandfather. Andrei's relations with Anton Fedorovich, a former Interior Ministry colonel, do not initially emerge. Andrew wants to go back to town. In the village, he befriends a local girl, Oksanka. Children spend a lot of time together. Oksana teaches Andrew to swim. Andrew meets the director of the local museum, Alexey Henrykhovich, who tells Andrew about ancient mounds with magnificent burials and ancient treasures near the village. Andrew and Oksanka decide to go in search of those treasures to raise money for surgery for their younger brother. The day before Andrew's arrival in the village, a jewelry store was robbed in a nearby town. During the search for ancient treasures, children accidentally attack a robber's trail. The stolen jewelry will be found and the thieves punished. Andrew will receive a cash reward from the store owner and spend it on his brother's surgery. Returning to the city, Andrew will realize that the summer spent in the village changed him, he began to grow older.