In theaters

STAR WARS, EPISODE III: REVENGE OF THE SITH, written and directed by George Lucas, 140 minutes, rated PG-13.

Of all the Star Wars merchandise flooding the marketplace – from the Mr. Potato Head Darth Vader to the Yoda Mini Magnet Figure to the Super Soaker Wookie Water Blaster (a must, I hear, for the 10-year-old set) – George Lucas blew it by not offering the one item some of us could have used while waiting in line to see his new film, “Revenge of the Sith.”

That would be the Lifesaver Lightsaber Umbrella.

The good news is that Lucas didn’t blow it where it counts. “Revenge of the Sith,” from the director’s own script, completes his prequel trilogy with a sense of mischief and fun before it dissolves into predictable rhythms of darkness and ruin.

There are few surprises here, but that’s beside the point. The film exists to seal the deal between 2002’s “Episode II: Attack of the Clones” and the movie that started it all, 1977’s “Episode IV: A New Hope.”

Some will view “Sith” as only a means to an end, but it is a crucial means to that end, at last offering a stage in which to view Anakin Skywalker’s intoxication with the Dark Side, his struggle to accept it, and his ultimate transformation into Darth Vader as a result. It’s an event that has become such a defining moment in pop culture, it helped to earn the movie a staggering $50 million at the box office on its first day alone.

As the film opens, Anakin (Hayden Christensen), Obi-Wan Kenobi (Ewan McGregor) and the Republic are soaring through space, fighting Count Dooku’s rebels in an effort to free Chancellor Palpatine (Ian McDiarmid) from the shifty, insectlike robot, General Grievous (voiced by Matthew Woods).

The battle sequence that ensues is fantastic, loose and brisk, boiling along the edges of the screen with exploding ships, smashed bodies and burning droids while the core steams with energy and wit.

All of this could have been another rote space battle for Lucas, but the director, employing the full weight of his computer graphics skills while peppering the action with genuinely clever touches, rises to the challenge and gives this space battle a fresh blast of life. For a moment, it’s as if he’s a young man again, but not so young that he has forgotten to tend to the family store. These scenes, after all, are tailor made for video game replication, which will net the billionaire Lucas a few more millions in sales.

Not content to linger on the opening rescue, Lucas pulls the story forward, lumbering a bit in the middle, with the short of it coming down to this: A coup is underfoot to form an evil galactic empire that will overthrow the Republic. Anakin is lured into the coup by the duplicitous Palpatine, who encourages Anakin’s gifts, strokes his ego in ways that the Jedi council won’t, and promises to give him the power he seeks.

For Anakin, the question comes down to that age-old struggle between good and evil. Audiences know which he chooses, but they don’t know why he chooses it. The movie answers in such a way that elevates him and condemns him, with a blister of madness festering at its root. Without giving anything away, Anakin’s decision humanizes him, confirming his love for his pregnant wife, Padme (Natalie Portman), and his deep need for the approval of a father figure, regardless of the cost, which turns out to be steep, particularly if you’re someone who would prefer to keep your looks.

As in “Attack of the Clones,” “Revenge of the Sith” exists in a digital world. It’s the work of computers crunching numbers, hard drives spooling terabits and a gathering of actors frequently asked not to react to each other or to a physical world, but to the sterility of a green screen.

When paired with Lucas’ formidable computers, those screens help to recreate all that’s not in the room with them. And so, not surprisingly, the sterility shows, as it’s bound to when the interaction between actors is limited or, in some cases, even excised.

Fortunately, this time out, the seams don’t show as easily as they did in “Clones.” That’s no thanks to the dialogue, which is just as stilted and as numbifying as fans have come to expect, but because Lucas has never been shy when it comes to pulling out the stops. That’s especially true in “Sith,” which becomes an action movie whose action has purpose, whose story deepens the franchise and whose themes trump the dialogue.

Other elements favor the film, particularly Yoda, who again bridges the gap between where Lucas has been and where he wants to go – straight into a completely digitized world with the heart and soul of the living. Also strengthening the movie is Lucas’ decision to give Anakin an extreme makeover. Gone is the heavy eyeliner, the white-trash rattail and the dishwater blonde mullet he favored in “Clones.” Now, mirroring “Sith,” his hair is slightly too long and far darker.

He’s older here, somewhat wiser, and while there are still traces of a whine in his voice, especially when things don’t go his way, that is overshadowed by a new confidence that carries the movie into its terrific ending, which cleanly and satisfyingly locks into the dock of “Episode IV.”

It’s here, on the volcanic planet of Mustafar, with the hell of lava erupting around them and the planet metaphorically splitting apart, that Anakin and Kenobi come to throws. It’s the best part of the film, as dark as Vader’s cape, as electrifying as anything in the series, with one man felled and the film’s PG-13 rating earned. Watching it and all of the ugliness that follows, you realize that sly Lucas has created his own coup.

He has stolen this trilogy back from the brink of disappointment and ended it with an intergalactic bang.

Grade: B+

Christopher Smith is the Bangor Daily News film critic. His reviews appear Mondays and Fridays in Style, and are archived at www.RottenTomatoes.com. He may be reached at BDNFilm1@aol.com.