Little kids are big money in Hollywood, so it was inevitable, after the first two movies took a billion smackers, that there would be a third Madagascar movie – and just as inevitable that the filmmakers would struggle with where to take it.

The original film from 2005 had a simple and elegant idea. Four animals escaped from the Central Park Zoo in New York and stowed away to Africa. It was like an animated inversion of The Wizard of Oz. Ben Stiller voiced a cowardly lion called Alex who had grown up with all the creature comforts in the zoo; Chris Rock was his brave and funky sidekick Marty the zebra. Jada Pinkett Smith voiced Gloria, a sweet-natured hippopotamus, and David Schwimmer was Melman the neurotic giraffe. They joined a squad of criminally inclined penguins heading back to Antarctica, and the whole circus ended up shipwrecked on Madagascar as guests of the certifiably nutty King Julien, ruler of the lemur kingdom (Sacha Baron Cohen).

The film was made by DreamWorks Animation, with gorgeously coloured CG animation and a strong nostalgia for the anarchic cartoons of Warner Brothers in the 1940s. It was much more Tex Avery than Walt Disney. The manic humour was perfectly pitched: it was innocent enough for the very small, but with stacks of verbal invention sailing over their heads into the ears of older, hipper youngsters.

The plot also made sense. Anyone could understand why animals raised in a zoo might pine for the plains of Africa. The second film took the menagerie across to Africa in a rickety jungle-built aeroplane powered by monkeys: another smash hit. The third film begins where it left off, with the monkeys and the penguins flying off into the sunset, leaving the original four behind, stranded. Instead of heading for Antarctica, the penguins go to Monte Carlo, because you can't trust a penguin with a pocket full of money. Or a pocket, for that matter.

Where then could the writers go, now that the original four animals are where they wanted to be, back in Africa? Why, let's go home to New York, cries Alex the spoiled lion, who's missing his daily steak dinners. Say what? But first, let's go to Monte Carlo and catch the penguins, so they can fly us all home.

If logic takes a back seat in the new film, does that matter? The whole series is based on gleeful silliness, so why worry about plot?

Well, here's why: in order to feel something for a movie, we need a floor of belief to stand on. "The animals want to return to Africa" is exactly that kind of floor. It's an emotional thing that underpins the characterisations, and emotions are one of the primary engines of stories. Going to Monte Carlo is enjoyably silly, but it cuts this film off from the real-world desires of the first two films. We are now in la-la-land, where the writers are intent on finding situations for comedy, rather than a story with its own momentum. That means the third film is colourful, manic, hilarious and meaningless. The ideas contradict each other, but who cares, let's have another car chase with lots of comin'-at-ya 3D effects, and a troop of flying Vespas! Yay!

How did the four originals get to Monte Carlo, one wonders? Forgeddaboutit! They join a circus to escape an unstoppable foe, a new character called Capitaine Chantel DuBois, of the Monaco Animal Police (voiced by the ever talented Frances McDormand). She wants a lion head to hang on her wall and she always get her animaux, whatever they are. This adds a new dynamic to the Madagascar stories, a chase game. It brings pace, action, humour – everything except meaning.

Some might say the series has become purer in its way, reduced to slapstick essentials. That's true: the energy is concentrated and the pace relentless, but this story makes no sense. Worse, it offers no wider questions: animals in zoos, animals in circuses, they're not prisoners, they just want to be there. Why would they go back to New York if they didn't want to be captives again? The first two films contained questions about the way humans treat animals, albeit deeply buried. The third film is cheerfully dumb about such things: enjoyably, loudly, in-your-face stupid, and proud of it.

Twitter: @ptbyrnes