"Men in Black 3" starts strong with the interstellar introduction of new alien villain Boris the Animal. As played by Jemaine Clement and designed by makeup whiz Rick Baker, Boris is a fearsome figure of intimidating size, teeth where you'd least expect, and a deep guttural voice.

He also represents the movie in a nutshell: looks cool, seems promising and goes absolutely nowhere.

"Men in Black 3" always sounded a little dicey. "Men in Black II" (yes, the sequel used Roman numerals) opened 10 years ago to a general consensus that it kind of sucked. It made $150 million less than the original in worldwide box office and maintains a decisively "rotten" score at Rotten Tomatoes (compared to the original's overwhelmingly "fresh" score). No one was clamoring for a threequel.

But Will Smith had an idea about time travel that he wanted to pursue and the studio, co-star Tommy Lee Jones and director Barry Sonnenfeld were all interested. So filming began in late 2010, without a finished screenplay. Production shut down soon after that and planned dates to resume came and went as tinkering continued on the script, co-star Alec Baldwin dropped out over scheduling conflicts and media reports surfaced that the movie was in deep trouble.

Consider it good news that what sounded like a complete disaster during production winds up nothing worse than a run-of-the-mill summer event movie on screen. It's an improvement over "Men in Black II," but not as fresh or inspired as the original. There's no real justification for its existence, but it's reasonably fun to watch most of the time. By the standards of summer 2012 so far, that's a win.

But don't get too excited. Moment to moment, "Men in Black 3" coasts by on colorful visuals, Smith's easygoing charm and Sonnenfeld's light directorial touch — at least until it's over, and you realize there's nothing actually holding the whole thing together. You've spent the last 100 minutes distracted by the promise of a payoff that never really arrives.

The movie works best in the present day, beginning with the aforementioned introduction of Boris and continuing through the reintroduction of Smith's Agent J and Jones' Agent K. They're still working for a shadowy organization keeping the world safe from renegade aliens. Agent J is still a motormouth and Agent K still never cracks a smile. They've got a new boss (Emma Thompson as Agent O), but otherwise it's as if they haven't missed a beat since we last saw them.

And yet suddenly — conveniently since the threequel needs some sort of emotional core to its story — J decides he really needs to know more about the enigmatic K. Why does this man never talk about his personal life, express emotion or demonstrate any kind of humanity? The key supposedly lies in his past.

Since Boris has discovered the secret to time travel and plans to alter the entire course of history that's where most of this story will take place. After a string of catastrophic events, J gets whisked back to 1969 in the film's single best set piece. Everything goes downhill from there.

Once J lands in the '60s, we're treated to some obvious but amusing racial humor (Smith may be one of the biggest movie stars today but he wouldn't have been so lucky then, and he milks the comic potential of a streetwise 21st Century black man transported to the "Mad Men" era), a random trip to Andy Warhol's famed Factory complete with Bill Hader dropping in as a one-of-a-kind Warhol, and a Cape Canaveral climax set during the launch of Apollo 11. That's pretty much it.

With so much of the action set in 1969, the filmmakers make the doubly dubious decision of robbing us of the proven Smith/Jones chemistry and failing to provide anything fresh or exciting in its place. Instead, Smith primarily plays opposite Josh Brolin as Young Agent K, doing a perfectly solid Tommy Lee Jones impression but struggling to uncover any intriguing angles to the purposefully underdeveloped character. He's also never able to click with Smith to the same degree as Jones.

Odd couple chemistry is as much a part of "Men in Black" as the kooky aliens and deadpan humor. As game as Brolin is, it's a shame how little we see of Jones here. There's no romantic interest this time around (Linda Fiorentino and Rosario Dawson are long gone, and Alice Eve is only fleetingly seen as a younger incarnation of Thompson's character), and screenwriter Etan Cohen (or whoever is actually responsible for the story) seemingly intends to shape this film as more of a "love story" between J and K in ways that never quite pay off.

Former cinematographer Sonnenfeld (who has been working mostly in TV after he followed "Black II" with forgettable family comedy "RV") remains a director stronger with visual style than storytelling finesse. Considering how worked over the screenplay reportedly was, it's somewhat surprising how straightforward the story develops. Even though the film makes hay with its absurd timeline (at one point the unmistakably fortysomething Brolin says he's 29; while the real life Smith was a newborn in '69, but his character apparently wasn't) there's a laser-like focus on J's mission that keeps the action consistently clear. Unfortunately, concise is not the same as interesting.

As eye candy "Men in Black 3" works fine. Sonnenfeld and his crew update the look of the original films to fit today's technology (for once the use of 3D in an event movie isn't entirely unwelcome) while smartly retrofitting other elements for the '69 timeline. The aliens are cleverly conceived — the sheer volume of creatures in an early Chinese restaurant scene is impressive, and I won't forget the creepy Cronenberg-esque opening on Boris' hand anytime soon — and the sound design is smashing. But all this great technical work is squandered on a story that settles for just OK.

"Men in Black 3" opens everywhere May 25