Marco Rossi, a young Italian boy in late 19th-century Genoa, endures his family’s financial struggles caused by his father Pietro’s charitable operation of a hospital. His mother Anna leaves for Argentina as a domestic servant to sustain them, but when her letters suddenly stop, Marco ventures across Latin America with his brother Tonio’s pet monkey, Amedeo, to find her.

Stowing away on a Brazil-bound ship, Marco confronts exploitation and unexpected kindness. In Argentina, Genoese acquaintances—like puppeteer Peppino and his family—aid his passage to Bahía Blanca, where he uncovers his uncle’s interception of Anna’s letters. Driven onward, he searches Buenos Aires, Rosario, and Córdoba.

Marco’s resilience shines as he forfeits train fare to save a dying girl, leading to a desperate train ride and abandonment in wilderness. Rescued by Roma travelers who gift him a donkey, he presses through the animal’s death and brutal landscapes to reach Tucumán. Gaunt and exhausted, he finds Anna critically ill; her revival upon their reunion allows vital surgery.

His odyssey, marked by steadfast resolve and empathy, intertwines with sailors, immigrants, and nomads, weaving themes of solidarity and tenacity. As a child enduring exploitation and societal indifference, Marco embodies innocence grappling with adversity.

Official adaptations preserve his tale’s core—familial love and ethical fortitude—with later films streamlining trials while upholding his perseverance and the poignant reunion.