In a small rural town in nineteenth century Belgium, young and poor Nello Daas, a self-taught artist, dreams of becoming a painter as great as his countryman, Peter Paul Rubens. Orphaned, Nello lives with his grandfather, Jehen Daas, and helps him with his meager milk delivery business. One day, while returning from town, Nello and Jehen witness a drunken hardware peddler brutally beating his dog. After the peddler leaves the dog to die, Nello and Jehen adopt him and nurse him back to health. The now strong dog, christened Leo by Maria Cogez, the young daughter of rich businessman Carl Cogez, steps in to pull Jehen's milk cart and relieves the sickly old man of his labor. Because of Leo, Nello finds more time to practice his craft and draw his favorite subject, Maria, who encourages him to enter a Rubens scholarship contest. Carl Cogez, however, disapproves of Maria's interest in the "ragamuffin" and, catching them together one afternoon, forbids her to see him. Despondent, Nello returns home only to discover that the hardware peddler has returned and reclaimed Leo in his absence. Before long, however, Leo fights to free himself and finds his way back to Nello. That night, Maria's parents host a lavish party to impress Pieter Vanderkloot, the snobbish son of a well-to-do family, and turn Nello away at the door. Maria, sneaking away from the party, apologizes to Nello and comforts his bruised ego. Satisfied that Maria still likes him, Nello returns happily to Jehen, but finds his grandfather dying in his bed. Jehen dies and Nello, now penniless, accepts Pieter's offer to buy one his drawings, unaware that Pieter wants to enter it under his own name in the scholarship contest. After welfare agents threaten to commit him to an orphanage, Nello runs away with Leo and hides out in the Cogez' hayloft. Sure that he will win the art contest, Nello is crushed when Maria tells him that the detested Pieter has won instead. Eventually, however, Maria uncovers Pieter's fraud and reveals Nello as the true artist. Convinced at last of Nello's worth, Carl chases after the fleeing Nello and brings him back to his daughter's side.