The images are opulent but the story’s an incoherent bore in “Kaena: The Prophecy.” But what else can you expect from a movie whose first line of dialogue is “We need more sap today”? These immortal words are spoken by a member of an unhappy group of humanoids inhabiting an isolated village on an alien world that turns out to be a gigantic floating tree. They’re slaves of a race of imposing beings, the Selenites, who call themselves the humans’ gods and demand that their servants collect sap from the trees for them; the village priest–one of those closed-minded religious figures whose unwillingness to question tradition leads to disaster, just as clerics are normally depicted in contemporary movies–orders his flock to obey their deities without question. Fortunately there’s one member of the community who thinks for herself–Kaena (Kirsten Dunst), a buxom young thing in a skimpy outfit–a sort of animated Lara Croft–who goes exploring while her more tradition-bound elders follow the rules and who thoroughly dismisses the village faith-system. In her peregrinations Kaena bumps into Opaz (Richard Harris), an avuncular fellow who’s the last of a race called the Vecarians and encourages her to fulfill her destiny by going up against the vicious queen the false village “gods” (Anjelica Huston). Also thrown into the mix are a young villager obviously intended as romantic interest for Kaena, the girl’s addled old grandpa, and a species of highly intelligent, talking worms called the Prosthetics. The latter are about the only saving graces in the convoluted narrative. All the other characters are stiff, dull and pompous, but some of these critters–especially one arrogant, supercilious fellow–at least generate a few laughs. Unfortunately they don’t play a large enough role in the movie’s last stages, which involve revelations about the six-hundred-year old connection between the Vecarians and the humans and a final march to freedom led by the redoubtable heroine.

The numbing complexity of this story is matched only by its curious familiarity; it seems to have been cobbled together from a score of earlier sci-fi epics by someone with more enthusiasm than skill. (The very opening, for example, is patterned after that of the first “Star Wars” movie.) The voice actors do what they can with the stilted, ponderous dialogue, but that isn’t much. Still, in lieu of tying to figure out, or care about, what’s going on and why, one can simply ignore the narrative and appreciate the elaborate visuals, which have a glossy, gold-brownish, caramel-colored sheen that makes them impressive if not terribly enticing. As the first feature made in France using computer-generated 3-D animation, “Kaena” certainly shows promise from a technical perspective, but it proves once again that content trumps style every time. Like another French product, that thoroughly empty live-action exercise in appearances, Luc Besson’s “The Fifth Element,” it wears out its welcome long before the final credits.