The film starts with Will Smith and Tommy Lee Jones, fighting crime in their familiar black suits. But then the movie takes a giant leap back in time, where we meet a young Jones played by Josh Brolin.
That twist puts in motion a plot that will not only surprise viewers, it just might bring some to tears.
"I'm really proud of how it works on an emotional level," said the film's director, Barry Sonnenfeld. "Will Smith has always said the third in a trilogy should be more romantic and emotional, and ours is."
Smith and Brolin say the movie has a lot of heart to it.
"That ending was the final creative link that I felt would make the entire movie come together," Smith said. "It's a sequel, but when you get to the end of the movie, you realize it's a prequel."
Brolin says he enjoyed this part over seeing the first.
"I like this one better because it has everything which is, I think, really cool, which is something you're going to say when you're promoting a movie anyway, but when you believe it, it's much easier to say it," Brolin said.
"Men in Black III" debuts this holiday weekend. It's rated PG-13.