Paris 1910. Emile, a shy movie projectionist, and Raoul, a colorful inventor, find themselves embarked on the hunt for a monster terrorizing citizens. They join forces with Lucille, the big-hearted star of the Rare Bird cabaret, and an eccentric scientist and his irascible monkey to save the monster (who turns out to be oversized but harmless as a flea) from the city's ruthlessly ambitious police chief.