Centuries from now, when the world is covered with water and humanity is extinct and the end of A.I. Artificial Intelligence becomes a documentary, the future computers trying to understand our civilization from the pop culture we’ve left behind will scratch their robo-heads at Mr. & Mrs. Smith.

Ancient records speak of the rise of some kind of symbiotic organism known as “Brangelina,” and then some years later its dissolution. The robots uncover an enormous fascination with this creature. There are thousands of pictures of this two-headed being smiling, looking glamorous, in front of backdrops festooned with corporate logos. Separately, the individuals that comprised Brangelina made many movies, but they appeared together only twice: In 2015’s By the Sea and in 2005’s Mr. & Mrs. Smith. In the year 2016 or the year 4016, the latter is one of the stranger works made in Hollywood in the 21st Century.

It was infamous before the public saw a frame of it, after stars Brad Pitt and Angelina Jolie fell in love on the set of the film and supposedly caused the breakup of Pitt’s marriage to Jennifer Aniston — a turn of events the movie seemingly acknowledges in its centerpiece action scene, when a fight between Pitt and Jolie systematically destroys their perfect house. These two, you see, are home wreckers.

Pitt and Jolie play John and Jane Smith, who’ve been married for five or six years (they disagree on the length of their relationship). They barely talk, and you don’t want to know about their sex lives. Their backstory is revealed through a clever flashback structure; conversations with their therapist tease out how they met (in Bogota, where they masqueraded as a married couple to escape the police) and fell in love. Despite their instant attraction, neither tells the other that they are elite assassins who kill people for money. Each hides their true self from the other (along with their weapons, which they hide in a spot their spouse is sure never to look; John keeps his guns in his tool shed while Jane’s are concealed inside the family oven). When the Smiths are sent to kill the same man and the hit goes wrong, they finally realize who they both really are — and are then ordered to kill one another.

Mr. & Mrs. Smith was supposedly written by screenwriter (and future X-Men Grand Poobah) Simon Kinberg as his Master’s thesis at Columbia University, and at times it does feel like a really high-end student film. The movie, which was directed by Doug Liman, has a great premise that it rarely exploits to the fullest. It’s got solid ideas, but some of them contradict one another. It’s a film about the tedium of domestic life drenched in fantasy imagery and starring two of the most glamorous people who’ve ever walked the face of the Earth. It rails against the way plastic suburban life chokes the passion out of relationships and it’s also a fairly tame, bloodless, nudity-free PG-13 Hollywood product. It imagines both this couple’s meet-cute and its inevitable demise — and then tacks on an unconvincing happily ever after. As the movie begins, the spark has gone out from John and Jane’s relationship, but John and Jane are played by two actors who very clearly want to f— each other every second they’re onscreen together.

What holds it all together are Pitt and Jolie, specifically because they so clearly want to f— each other, and that intense attraction radiates off the screen (and through the movie’s dicier sequences) like nuclear material. It’s a shame that Pitt and Jolie only made two films together, because they could have been on the Mount Rushmore of Movie Couples. They truly seem like equals: Physically, comedically, emotionally, and sexually. And Pitt, who has several sublime moments of improvised physicality, has zero ego about being upstaged by Jolie, who repeatedly proves herself to be the tougher, stronger, and better assassin of the pair.

Our collective fascination with Brangelina brought audiences to the theater to see Mr. & Mrs. Smith in 2005 (the movie was the year’s 10th biggest hit, outgrossing the first Fantastic Four and The 40-Year-Old Virgin). Voyeurs hoped to look beneath the film’s fictional surface to find some hint of the reality of the couple’s relationship. 10 years later, its metatextual echoes are even more pervasive. This goofy action thriller about a pair of married assassins seems to anticipate nearly every phase of Pitt and Jolie’s relationship, from instant attraction up to and including its ugly end.

One rumor this week alleges that Jolie sent private eyes to spy on Pitt on the set of his new movie Allied, a scene that Jane plays out in Mr. & Mrs. Smith when she studies surveillance footage and discovers John has been lying to her throughout their entire relationship. Just about the only part of the Brangelina odyssey that doesn’t factor in some way into Mr. & Mrs. Smith is their large blended family — although even that is alluded to in an alternate ending that didn’t make the final cut.

The actual last scene of the movie is happy: John and Jane reconcile and talk cheerfully with their therapist one last time. But in 2016, their formerly triumphant conversation carries additional weight:

“Sometimes you have to battle through.”
“That’s marriage, right?”
“Yeah, you take your best shot.”

As weird as this stuff was in 2005, it’s even more surreal now. In the years ahead, critics will surely focus on By the Sea, Jolie and Pitt’s 2015 film about a troubled marriage, as the one that contains the most insight into their relationship. But future bots on the ruined Earth of 4000 A.D. will find more in Mr. & Mrs. Smith, one of the great, bizarre cinematic artifacts of our time.