Atilio lives with some of his daughters and her granddaughter Iara alongside the river. His great desire is to have a grandson to transmit the secrets of fishing, his language and Guarani culture. Iara's mother, Helena, lives in Buenos Aires 1,100 km away. Atilio discovers in a letter that Helena is pregnant with a boy. He decides to take Iara against her will to Buenos Aires, with the hope to bring Helena so the boy is born in Paraguayan land.