Flup, a canny Brussels street kid, is run over by a car but he is lucky in his misfortune. Indeed Vierset, a wealthy banker and his daughter Jenny, feeling guilty for what has happened, decide to adopt the ten-year-old orphan. For a time life could not be sweeter for Vierset, Jenny and Flup. Unfortunately the street urchin's benefactor gets drowned in a shipwreck and, to make matters worse, Flup's legal guardian kicks him (and Jenny) out of the banker's gorgeous mansion. Jenny sinks into depression but not Flup who has not yet said his last word...