When the stakes are high, Nod (Josh Hutcherson) discovers what it takes to be a true hero. (Blue Sky Studios)

In calling itself “Epic,” the new CGI adventure based on children’s author and illustrator William Joyce’s “The Leaf Men” might be guilty of overselling itself, just a bit. Yes, the movie is certainly more swollen in scope and tone than Joyce’s eco-themed picture book on which it’s (very loosely) based. That 2001 story of the secret, teeming life of a garden had a charm similar to the author’s earlier “George Shrinks,” in that both books derived much of their enchantment from imagining what the world looks like if you’re only an inch tall.

Yet this film, on which Joyce worked as producer, writer and production designer, retains enough of the magic of the original to make it enormously visually appealing, even if the story itself is almost unrecognizably bloated.

As in the book, the Leafmen are a race of bug-size soldiers who maintain the order and balance of the natural world. Riding saddled hummingbirds, they keep the forces of decay and rot — embodied by creatures known as the Boggans — at bay. But when Mandrake (voice of Christoph Waltz), the evil leader of the Boggans, attacks the Leafmen’s queen (BeyoncéKnowles) and steals the magical flower bud containing the soul of her replacement, the Leafmen must fight to get it back before its power is perverted into poisoning all life.

Aiding the Leafmen in their mission is Mary Katherine (Amanda Seyfried), a human teenager who has accidentally been shrunken down to their size. The requisite chaste romantic subplot comes courtesy of a rebellious adolescent Leafman, er, Leafboy (Josh Hutcherson), who likes Mary Katherine but also needs to learn a few lessons about teamwork and community before everything is wrapped up with a neat little bow. Never mind that it’s more than a little weird for a human to be dating someone the size of a praying mantis.

Comic relief is provided by a wisecracking slug (Aziz Ansari) and his snail pal (Chris O’Dowd). The bantering gastropod molluscs are pretty much the funniest things about the movie, which like last year’s “Rise of the Guardians” (also based on a Joyce book) has a pervasive dark overtone. Mandrake, a villain who swoops around on a crow while wearing a dead animal hide and shooting acidic goo out of his bazooka-like staff, is scary enough to give a sensitive little kid nightmares. Waltz does a nice job — maybe too nice a job — of conveying pure evil.

The rest of the voice cast is fine, if not quite as distinctive. Jason Sudeikis plays Mary Katherine’s father, a dithering scientist who’s alone in suspecting that the forest is alive with unseen critters. Colin Farrell makes a strong Leafman leader, Ronin, and Aerosmith’s Steven Tyler turns in a memorable cameo as a caterpillar, Nim Galuu. Physically, and personality-wise, Nim may remind some older viewers of the caterpillar character from “Alice’s Adventures in Wonderland,” and not only because Tyler sounds like he has been smoking a little something.

The action proceeds predictably, with elements of “The Borrowers,” “FernGully: The Last Rainforest,” “The Ant Bully” and other Tiny Town-themed tales mixed together. It’s a little unfortunate that the plot has to turn decay into the bad guy, instead of teaching children that decomposition is part of the cycle of life. Still, if “Epic’s” plot is less than wholly original — not to mention more than a little unscientific — the visual design is fairly stunning, underscored by an effective use of 3-D.

It may not be epic, but it’s eye-popping entertainment.


PG. At area theaters. Contains cartoon violence, peril and death. 110 minutes.