(Un monstre à Paris)
Parijs, 1910. Shy movie theater operator Emile accompanies his boisterous friend, would be-inventor Raoul, who delivers goods by sunflower oil-powered truck, with a shipment to an absent botany professor's lab where the devoted monkey assistant Charles fails to prevent flippant Raoul experimenting against clear written warnings with seeds and super-fertilizer to accidentally create a giant plant and a monstrously magnified flee that breaks trough the hot greenhouse roof. The roofs-leaping monster causes panic throughout the inundation-plagued city, so police prefect Maynott considers it the ideal diversion from regular police problems and an opportunity to enter the mayoral election race as the hero who caught it. Raoul has a furiously denied mutual crush -like Maynott- on nightclub singer Lucille, who meets the monster, finds it cute and gets the gang to try hiding it, and help it escape when Maynott finds its trail and won't be stopped, not even by grave danger for people.