This is the story of a man who created a jungle next to the highway, building with his bare hands beautiful and unbelievable works of engineering in the forest. He is known as Tarzan from Argelaguer because of the peculiar Tarzan remakes recorded with the collaboration of a 14-year-old boy. Sobre la Marxa puts together the pieces of an extraordinary life of numerous facets: the aged man who is still a child at heart, the modern savage, the visionary admired for those who go on a pilgrimage to his forest, the misunderstood to whom many labelled a lunatic.