-By Ethan Alter

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Here's a hypothetical scenario to gauge how you might respond to Avatar, James Cameron's highly anticipated return to filmmaking after over a decade in the wilderness. Picture yourself walking into a second-hand bookstore and heading straight for the science-fiction section. Lining the shelves in front of you are hundreds of tattered paperbacks from the ’50s, ’60s and ’70s bearing titles like The Time of the Hawklords and Cosmic Crusade above evocative illustrations of giant robots, alien landscapes and other such genre touchstones. Thumbing through the books, your hand stops on a volume with the intriguing name Avatar. On the cover is a picture of a ten-foot tall, blue, cat-like humanoid in warrior garb riding atop a resplendent alien pterodactyl and firing an AK-47 at a large military helicopter filled with human soldiers.

Now, based solely on that image, do you buy the book or not? If the answer is yes, then you'll probably flip for Cameron's film. If you opt to put it back on the shelf...well, there's still lots of stuff here for you to enjoy, but you may not come away as wildly enthusiastic about the experience. Because the dirty little secret of Avatar—which, as we're constantly being reminded, is the most expensive movie ever made—is that Cameron has used all that money and state-of-the-art technology to create the ultimate pulp sci-fi novel, the kind of tale that would have sold for 50 cents four decades ago. It's easy to poke fun at those stories now, what with their stock characters, overheated prose and dubious science that trends more towards fiction. And yet, the imagination contained within those pages still impresses, as the authors conjure up new worlds, cultures and species that inflame readers' fantasies, making them want to book the first rocket to Mars, Nidor and beyond.

With Avatar, sci-fi fanatics can add Pandora to their interstellar itinerary. This beautiful planet, located a mere 4.4 light years away from Earth, boasts lush jungles populated by all manner of exotic creatures, giant trees that can house entire communities, and mountains that literally hang suspended in the sky. It's also home to a friendly, if fiercely protective, alien race known as the Na'vi—the aforementioned ten-feet-tall, cat-like humanoids—as well as a valuable mineral Earth's scientists have unimaginatively chosen to call Unobtainium. Cameron created this world through a mixture of motion-capture techniques and computer-generated animation, and while the finished product isn't exactly photorealistic like the pre-release hype suggested, it actually achieves something better—a compelling heightened realism.

The director has deliberately designed Pandora to superficially resemble Earth, but he then uses the freedom allowed by animation to enhance the planet's landscape and its inhabitants, adding a wealth of details that make it its own distinct entity. At the same time, he avoids visual flourishes that might render this alien environment too fanciful, too much like a cartoon. As a result, Pandora feels like a living, breathing world and Cameron is its creator and most enthusiastic tour guide. In fact, there are several sections in the movie where the plot stops dead in its tracks to give the audience plenty of time to marvel at the planet he and his teams of digital-effects artists have built from the ground up. In these moments, Avatar acquires the feel of a Terrence Malick film; Cameron revels in the flora and fauna of Pandora in much the same way that movies like The New World and Days of Heaven rhapsodize unspoiled American landscapes.

It's just as well that Cameron takes frequent narrative time-outs during the course of Avatar's 163-minute running time, because, quite frankly, the story he's chosen to tell is serviceable pulp fiction at best. All sci-fi serials require a square-jawed hero and here that role if filled by Jake Sully (Sam Worthington), a crippled ex-Marine who is dispatched to a mining colony on Pandora to participate in the Avatar Program, where his consciousness is downloaded into a lab-grown Na'vi body. The scientists who run the program, including Dr. Grace Augustine (Sigourney Weaver), intend for him to be an agent of peace, but the outpost's military commander, Colonel Miles Quaritch (Stephen Lang), has other plans. Apparently, a Na'vi tribe is residing on top of one of Pandora's largest deposits of Unobtanium and the corporation that oversees the mining efforts wants them gone. Sully is tasked with infiltrating the tribe in the guise of his alien avatar and gaining their trust, all the while assessing their strengths and weaknesses for a possible invasion. And because every square-jawed hero needs an exotic love interest, enter the Na'vi warrior princess Neytiri (Zoë Saldana), who at first finds herself at odds with this strange interloper, but gradually succumbs to his charms.

Like George Lucas, Cameron is one of those writer-directors who would benefit from passing the writing chores off to another party and yet stubbornly continues to pen his screenplays himself. On the whole, the dialogue in Avatar is far less turgid than what moviegoers endured in the Star Wars prequels, but the script still contains its fair share of clunkers. Of course, the case could be made that cheesy dialogue is another important part of the sci-fi pulp tradition. Besides, subtlety and nuance have never been among Cameron's strengths; whether it’s action, romance or comedy, he can't help but go big and broad. The thing that distinguishes him from other directors of spectacle-driven blockbusters like Michael Bay and Roland Emmerich is that he anchors his epic visions around basic, relatable emotions, which he handles with the utmost sincerity. Avatar, like Titanic before it, may inspire occasional fits of giggling and eye-rolling, but its earnestness is preferable to the soulless machinery of Transformers: Revenge of the Fallen.

It doesn't hurt that Cameron remains one of the best action shooters in the business; the film climaxes with a sustained battle sequence that lasts almost 40 minutes and is truly a wonder to behold. Scenes like this one are guaranteed to hook general audiences, but in the end perhaps only sci-fi fans will be able to fully appreciate what Cameron has achieved with Avatar. He's produced a film that straddles eras, pointing the genre to a new future while also celebrating its past.