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, an eccentric scientist and his irascible monkey to save the monster, who turns out to be an over-sized but harmless flea, from the city's ruthlessly ambitious police chief.