Picking up where Shark Tale ends, all the characters of the film dance at the whale wash in a spoof of Saturday Night Fever.

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

Oscar is a small fish whose big aspirations often get him into trouble. Meanwhile, Lenny is a great white shark with a surprising secret that no sea creature would guess: He's a vegetarian. When a lie turns Oscar into an improbable hero and Lenny becomes an outcast, the two form an unlikely friendship.