A scene from Downsizing.

I watch a lot of movies. Like, a lot of movies, and it’s very rare for me to be thinking halfway into a movie: “Say, this could be one of the year’s best films!”—only to have it become one of the year’s worst films in the second half.

Well, that’s what happened when I watched the latest Matt Damon vehicle, from director Alexander Payne (Election, Sideways), the horribly off-balance Downsizing.

The film starts as brilliant satire mixed with science fiction: Scientists have discovered a way to reduce energy and resource consumption on our planet by shrinking people and putting them into miniature utopia communities. By doing this, not only do humans generate less trash; they essentially become rich when their finances are transferred into the downsized communities. A standard bank account goes from being worth thousands to millions.

Damon plays Paul, an occupational therapist at Omaha Steaks living from paycheck to paycheck. He and his wife, Audrey (Kristen Wiig), are tantalized by the idea of getting out of their crowded house and into something a little roomier with a nice pool—plus becoming millionaires. They decide to take the plunge to get small. Paul completes the process and miniaturizes, but Audrey has some complications during the head-shaving part—so Paul winds up all alone in a newly shrunken world, and he’s completely pissed off.

Through this point, the film is everything you’d want out of this kind of movie. It’s clever, with Damon using his laid-back comic charms in service of a screenplay that’s full of interesting insights. Visually, it’s a triumph: The scenes of full-sized adults chatting with mini people are seamless. To say that I was impressed would be an understatement. This movie was racing up my Best Of 2017 list.

Then … Downsizing rapidly disintegrates into utter boredom and nonsense. The filmmakers apparently didn’t know where to really take the story after Paul enters the shrunken world, and the movie gets politically obvious, even stereotypical, in depicting Paul’s new world problems.

The second half starts off with Paul’s dating woes. This scenario has potential, and probably could’ve worked as the crux of the final acts—not as good as the promising first half, but it’s cute enough to be entertaining. But when Paul meets Ngoc Lan Tran (Hong Chau), essentially an illegal shrunken immigrant, warning alarms start going off: The movie wants to hammer you on the head with some kind of grand message. Downsizing tries to become some statement about how typical problems would most certainly follow us into the shrunken world, because humans are the same big and small. Yeah, OK. That’s fine. This is supposed to be fantasy/satire.

But instead of continuing as biting satire, the movie becomes afraid of itself, and Payne tries to make a feel-good message movie that winds up insulting our intelligence. It drags on forever as Paul travels to the original “shrunken person” colony in attempt to save the species. None of this works, and whole enterprise feels like two movies—one good, one really bad.

I do believe Payne could’ve found a way to mix Paul’s tribulations with worldly problems, but what he’s come up with is so heavy-handed and predictable that it trashes all of his good intentions. This is not a movie that deserves a happy ending. It had a chance to really say something about the damage selfish humans inflict upon the planet and themselves, but it opts to go all touchy-feely.

Matt Damon … other than that awesome Thor cameo, 2017 just wasn’t your year.

Downsizing is playing at theaters across the valley.