The trajectory of any story is as important as the characters, the plot, the moral, anything. The trajectory of “Suburbicon” is one of mood and atmosphere.

When I saw it, knowing only that it starred Matt Damon and was directed by George Clooney, I was taken for an ever-changing mood/atmosphere-fueled ride. Set in a Rockwell neighborhood of neat houses and trimmed lawns in the late-1950s, all is light and bubbly. The mailman knows everyone’s name, the colors are bright, the soundtrack music is reminiscent of what was heard on every TV sitcom of the time.

Then there’s a shock to the system. A black family, William and Daisy Mayers (Leith Burke and Karimah Westbrook) and their young son Andy (Tony Espinosa), move in to what has been an all-white enclave. This doesn’t sit well with any of the suddenly uncomfortable neighbors, or even with the mailman.

What springs out of this is a tale of racial turmoil, a story of a nice, innocent family being caught up in the unreasonable fear their presence creates in others. It’s based, to some extent, on a true event that happened in Levittown, Pennsylvania, to a black family in 1957, and was turned into a script by George Clooney and his producing and writing partner Grant Heslov.

But there’s more ... a whole other story intertwines, in the most ironic of manners, with that one.

One of the families, living in the house right next to the Mayers, is comprised of Gardner and Rose Lodge (Matt Damon and Julianne Moore) and their young son Nicky (Noah Jupe). There’s no racial animosity to be found among the Lodges; they have other things to be concerned with. Rose has been confined to a wheelchair after a mysterious car accident, so her twin sister Margaret (also played by Moore) has come by to help out, to be a sort of mother figure to Nicky, to keep Gardner company, to coldly watch her sister.

The film’s mood has quickly gone from happy to less happy. After a late-night visit by a couple of brutal thugs at the Lodge home, involving people being tied up and chloroformed, and the accidental death (there’s that “accident” business again) of Rose, everything turns dark, then darker. That trajectory has been set, and it’s not going to stop until it gets to utter nastiness.

The music has changed from sprightly to suspenseful, evoking the spirit of Hitchcock composer Bernard Herrmann. Margaret offers to move in and help keep things somewhat normalized, but she seems more interested in the welfare of Gardner than of Nicky. Neighbors decry the fact that “nothing like this ever happens here; this is a safe place,” even while most of them start tormenting the new black neighbors, gleefully letting their violent actions escalate.

Yet there’s still lightness to be had in this movie brimming with ever-increasing darkness. Good guy Uncle Mitch (Gary Basaraba) comes by to make sure Nicky is OK, and to promise that he will hunt down and kill whoever killed his sister Rose. The introduction of a claims investigator (Oscar Isaac) who’s checking into the “red flags” surrounding Rose’s death leads to a couple of scenes between Isaac and Damon that reach areas of comic absurdity.

The film’s positive ingredients include terrific performances by Damon, who hasn’t mined this sort of territory for a character before; by Moore, who has previously portrayed her share of less-than-honorable people; and by Noah Jupe, who gains our sympathy as we see much of the story through his eyes. Though the two separate stories sometimes have a jarring feeling as they sit next to each other, Clooney is getting more confident behind the camera, and it’s clear that he knows and gets exactly what he wants in the direction of them.

But back to that trajectory. It isn’t revealed till the end credits that the murder mystery part of the story comes from an almost 30-year-old script by genuinely twisted Joel and Ethan Coen. Which is a main reason that everything smoothly turns from light to dark and violent. OK, that explains it.

— Ed Symkus writes about movies for More Content Now. He can be reached at esymkus@rcn.com.

“Suburbicon”

Written by Joel Coen, Ethan Coen, George Clooney, Grant Heslov; directed by George Clooney

With Matt Damon, Julianne Moore, Oscar Isaac, Noah Jupe

Rated R