Horizonte tells the story of João, a seven-year-old boy born in Paradela, who dreams of seeing the sea. From a very young age, he has begged his parents to give him that joy, but money is scarce in the family and, as if that were not enough, Paradela is the place furthest from the sea in Portugal.

Unwilling to give up, the boy begins to consider his options. He knows that setting off on such an adventure will be a tremendous challenge, but his desire is so strong that he ultimately embraces the risk. He packs a bundle of clothes and food, ties it to a stick, and sets out on a journey—a journey marked on the map in a straight line to Esposende, a place whose name means nothing to him at first, yet immediately takes on a mythical dimension, like Mecca.