With “Foe,” writer-director Garth Davis gives himself a challenge he can never quite overcome. He chooses to make a film set at a future time when life on Earth has little promise, hope or joy. He takes us to a place no one would want to be, and yet it’s his job to make us want to be there.

He can’t succeed, but he comes closer than you might expect.

“Foe” is somber, depressive and suffocatingly oppressive, though not boring. Or to be more accurate, it’s never boring long enough to make us give up on it.

Throughout the film, there’s usually something going on that’s of interest or of potential interest. Even at its best, it’s not what anyone could call enjoyable, and nothing anyone would want to see twice, but it has a certain integrity of intention. Davis tries to do something serious and impossible, and fights it to a draw.

What I respected most about “Foe” — and perhaps you’ll enjoy it more if you know this going in — is that it’s a movie about a marriage. That specific focus is camouflaged, at first, by other elements: It’s set in 2065, at a time when the entire Midwest has become a sandpit because of climate change, and artificial intelligence has advanced to the point that robots and people are practically identical.

But the real essence of “Foe” is the story of a relationship slowly, but definitely, beginning to fracture.

Hen (Saoirse Ronan) and Junior (Paul Mescal) live in a house in the Midwest, surrounded by nothing, and they see absolutely no one but each other. Every day is the same.

母鸡想搬到城市和生活with more adventure, while Junior wants to stay on this land, which has been owned by his family for generations. As we watch, we might ask ourselves, “Do they just need a change in circumstances or a change in spouses?”

But before they begin to work out their problems, a more immediate threat arrives in the form of a government agent (Aaron Pierre), who informs them that Junior has been drafted into a special space unit. He will go away for two years as part of a project to make another planet habitable for human beings, just in case Earth needs to be evacuated.

“Foe” is not an especially long movie, but it feels like it because it should be 90 minutes, and instead it’s 110. The burden of the extra running time falls on Mescal, who, at one point, is called upon to make a long, contrived speech in which he has to sob and rave and punch the walls until his hands are bloody. (Perhaps he’s trying to punch his way out of the movie.)

Then just as it seems like the movie has come to a standstill, it revives. Eventually, the movie gets somewhere, and it ends well.

It would be easy to dismiss “Foe” as a lugubrious downer, except that the reality of its world feels palpable and that marriage seems real. I believed Ronan and Pescal as two people bound up in love, shared history and torment. As much as I was as glad as anybody when “Foe” finally ended, those two unhappy people have stayed with me.

Reach Mick LaSalle: mlasalle@sfchronicle.com