It's been 15 years since Tommy Lee Jones and Will Smith first got together to save the world from aliens. They reunited in 2002 for a not-so-inspired sequel that was more of a rehashing of the original gruel than it was anything new or inventive.

Skip another decade and dust off the franchise for another go-round, and, just to keep the math complicated, have the bulk of the story take place 43 years ago. So, Men in Black times three installments divided by 15 years equals 1969 to 2012.

OK, if that's all a little confusing, I apologize. Math is not my strong point. You could always travel back in time to my high school algebra class and tutor me, causing my future to be altered, so I could become a brilliant mathematician. Actually, I'd rather if you didn't, because I'm really not that fond of math, and I'd hate to risk ripping a big hole in the time/space continuum for something I don't really care about in the first place. If we're going to time-travel and change the course of history, let's have it be for something really important, like stopping disco music from becoming popular, or beating up the guy who invented neckties.

Of course, time travel is a silly concept and could never actually work. Which is apparently why we seem to love movies that involve time travel so much that every couple of years we make a few more. All of them have gaping holes in them, all of them are, on some level, ridiculous, and all of them seem bent on using the device in a way that isn't supposed to be ridiculous and will sew up all of the holes. It never works out that way, but they keep making the movies and we keep watching them.

The only possible exception to that is, in case you're wondering, an extremely funny short film called Time Freak. It was nominated for an Oscar in 2012 but didn't win, but you can find it on iTunes and download it for a nominal fee. Seriously, this is the best time-travel movie I've ever seen, and if you buy the download and are not completely satisfied, I will personally go back in time and stop you from watching it in the first place by re-writing this column without mentioning it, effectively giving you a refund.

Men in Black was an exciting and often amusing movie, surprising us with just how close we brush with aliens every day, and making us grateful that the men in black are out there doing their job. Men in Black II forgot, as many sequels seem to do, that plot was paramount. Director Barry Sonnenfeld seemed content to play off of sight gags and rely on schtick to sell the goods. Sadly, there were no goods, just a series of jokes with some familiar characters in some familiar situations but nothing to write home about. It almost seemed like the whole movie could've been stuck on the first DVD in the "deleted scenes" section.

So now we know that the period of penance for making a lousy sequel is apparently ten years, and Sonnenfeld has sufficiently repented to bring us a much more worthy follow-up in the form of Men in Black 3.

The movie starts with a rather creepy alien called Boris the Animal escaping from a maximum security prison on the moon, Lunarmax. He was originally incarcerated there by Agent K (Tommy Lee Jones) back in 1969, and the arresting altercation also cost Boris his left arm. It was also at that time that K deployed a protective shield around the Earth (ArcNet) which has heretofore protected all of humanity from the Bogladites, of which Boris is now the sole surviving species representative.

Boris has had four decades to plot his revenge, and breaking out of prison is just the first step in his diabolical plan to have the Bogladites invade and destroy the Earth. Step two is going back in time to 1969. Step three is killing Agent K before he a) cuts off Boris's arm, b) kills Boris, and c) deploys the ArcNet. Meanwhile, Agents J (Will Smith) and K are up to their usual oil-and-water partnership routine, except that they have to attend the funeral of their former director, Z.

K delivers the eulogy, a flatline presentation so short and devoid of emotion it surprises even J, who has grown quite accustomed to his curmudgeonly companion's mannerisms over the years. This leads to a bit of an argument between the two, and later that evening they have an abbreviated phone conversation that ends with J hanging up on K when K can offer no explanation for his sour outlook on life.

At about the same time, Boris the Animal manages to check off step two of the evil plan and travels back in time to Coney Island in 1969. J is at first unaware that anything wonky is going on until he drops in at K's apartment to find it occupied by a young family. Arriving at work, no one seems to know anything about K and all seem a little concerned by J's bizarre behavior. The new director, O (played by Emma Thompson), explains to J that K died in 1969 at the hands of Boris the Animal.

Then, because of J's sudden craving for chocolate milk, O correctly deduces that someone has fractured the time/space continuum. This, then, leads J to follow Boris the Animal's tracks to an electronics store, where he manages to obtain a time-traveling device that allows him to jump back to 1969 by jumping off the Chrysler Building, arriving 24 hours before Boris.

J manages to catch up to Boris, but is apprehended instead by a very young Agent K, played by Josh Brolin, whose dead-pan, dead-on characterization of Tommy Lee Jones is remarkable and hugely entertaining. K is naturally distrustful of J, and almost neuralyzes him before J finally convinces him that he is from the future and he's come back in time to save the world.

The pair's subsequent adventure is fun and often funny as they race against time, literally, to try and catch both the two-armed Boris and the one-armed Boris before they can realize their very bad alien plans. J is amazed and amused by how much more jovial and likable his partner is as a young man, often wondering aloud, "What happened to you?"

The answer to that question is actually a crucial plot point that I will not reveal in this review, as it would require my revealing the ending in its entirety, and that would suck a great deal of the sweet sticky off the cinematic lollipop.

MIB-3 is a good film that deserves to be seen as the true follow-up to the first film. Skip number two entirely. You might think this is a kids' film because of the funny aliens and such, but it is definitely not for little folk. Besides a few sort-of-scary moments, the language is not geared for sensitive ears, and there is more swearing in this one than in either of its predecessors.

It has many of the sensibilities of the first film that made it fun and exciting, but it also has a sweet backstory that makes the relationship between J and K more than it has been. In a story seemingly all about aliens, it is ultimately our heroes' humanity that makes this movie worth watching.