Besson, best‑known for live‑action extravaganzas such as “La Femme Nikita” and “The Fifth Element,” concedes he knew nothing about animation before directing “Arthur,” which is based on a visual world created by comic‑book author Patrice Garcia. His wife, Celine Garcia, co‑wrote the script with Besson.

The lesson is: Don’t let an animation amateur direct a cartoon flick.

The movie opens with a live‑action prologue as young Arthur (Freddie Highmore of “Charlie and the Chocolate Factory”) and his grandmother (Mia Farrow) face eviction from the family homestead by a scheming land developer.

The only solution is a cache of rubies hidden away for some reason by Arthur’s grandfather (Ronald Crawford), an engineer and adventurer who vanished a few years earlier. Gramps left behind clues to lead Arthur to a group of little people called the Minimoys, tiny elves living in the family’s garden who hold the key to finding the jewels.

In a whirlwind of muddled action, Arthur is shrunk to Minimoy size, with most of the remainder of the movie playing out through computer animation. Arthur actually transforms into a pointy‑eared Minimoy with a bizarre shock of white hair, a punk‑rock outfit, and strange new powers such as the ability, like his namesake from Camelot, to pull a magical sword from a stone.

Minimoy Arthur weaves back and forth from looking cute and creepy, as do the other denizens of this miniature realm, including the King (De Niro), his mischievous son (Jimmy Fallon), an aide (Harvey Keitel) and a couple of Rasta‑esque good Samaritans (Snoop Dogg and Anthony Anderson).

The exception visually is the princess, Selenia (Madonna), whose character is endowed with eerily human facial expressions and is one of the most luscious animated babes ever created.

Arthur certainly thinks so. He’s immediately smitten, and Selenia gradually returns his amorous feelings.

Granted, these are just cartoon figures, but there’s something mildly unsavory about a 48‑year‑old woman and a 14‑year‑old boy providing voices for characters who have the hots for each other. Madonna’s character is 1,000 years old, Highmore’s is an adolescent, and you almost expect Arthur to mutter, “Miss Selenia, you’re trying to seduce me.”

Through madcap, turgid action sequences, Selenia and Arthur lead an expedition to foil a plot by a warped villain (Bowie) to destroy the Minimoys. Striking images occasionally leap out, and the animation outfit BUF Cie has crafted a unique world, but the quick‑cutting visuals and vague story are such a jumble that it’s hard to even want to make sense of the movie.

Things do end on a positive note, Besson and company adding a very clever animated curtain call in the closing credits. Not the best place for the highlight of your film, but at least it’s something.

“Arthur and the Invisibles,” released by MGM and the Weinstein Co., runs Two stars out of four.