Heaven Knows What fills the screen with the sort of occurrences that urban bureaucrats work tirelessly to obscure: drunken kids verbally laying into each other from opposite sides of the street. Homeless people cycling through all-night stores—perpetually stalked by hired help—searching for a stand isolated enough to steal from. Or a drug-addled beggar nodding off high behind an empty bucket. Sure, we can throw aspersions at those interested in covering these people up, but how often do we do anything more than drop a few coins their way ourselves? This is movie made up of the places, the actions, and the people that we look away from.

We’re in New York City, but a more accurate description of the setting would be to say we’re “street-level.” The film—directed by Ben and Josh Safdie, shot by cinematographer Sean Price Williams—starts by staring at Harley (debuting actress Arielle Holmes) as she contends with twin addictions. One is to Ilya, with whom she shares a room at a couple’s shelter. The other is to shooting heroin. We catch up with her en media res, so we don’t know if Harley chose the drugs, the crime, the day-to-day uncertainty—or if it chose her. All that matters here is that she’s in it.

Before the opening credits start, she slits a wrist, searching for catharsis in vain after cheating on Ilya. Before they finish scrolling on screen, she’s out of the hospital and back on the street, pushing Ilya out-of-mind while she fiends for her next fix. She turns to Mike (Buddy Duress, another non-professional), a dealer who’s both small-time enough game-wise and smitten enough Harley-wise to front her a dose or two per day. Though considering his low station in the hierarchy of street dealers, handing out free bags probably isn’t an advisable move. Duress has the thinned-out droop face of a man who eats most of his meals off the value menu.

If Ilya is Harley’s rockstar stud, then Mike is her stoned-out steady. There’s a charming bluster to Duress’ performance, betraying that the character’s heart is a notch or two softer than he’d care to admit. (There are three moments of horrific violence in the film, one for each of the primary characters. When Mike gets his, it’s met not with fury, but with an incredulousness that borders on the goofy.) Harley maintains a similarly guarded softness. Battle-hardened though she may be, she seems to indulge the belief that she’ll eventually be carried out of this asphalt dungeon. She rides a rival dealers’ motorcycle like a Disney Princess riding horseback—her eyes taking in the setting sun, imbued with misguided hope, convinced someone will eventually lead her to the right side of the street.

That hope is, by all accounts, the genuine article. Josh Safdie met Holmes while scouting locations for an unrelated movie about New York’s Diamond District. He spied this raggedly beautiful girl—who could pass for the disaffected daughter of a wealthy merchant any day of the week—and then he found out she was living on the street. Like Harley, Holmes was homeless and addicted (to both heroin and a real-life Ilya), and appeared quietly driven to escape it. The brothers, perhaps selfishly, asked her to write about her experiences. She typed a scroll she called Mad Love in New York City. And then the Safdies adapted it into Heaven Knows What.

That alone is a story fit for cinema screens—in fact, it already was. The Coolidge Corner Theatre will be playing one of comic auteur Preston Sturges’ most enduring pictures on Monday night, the screwball Hollywood-satire Sullivan’s Travels, which plays out a plot eerily similar to the aforementioned Safdie scenario. Joel McCrea’s title character is a director who decides his next picture needs to dramatize the lives of those noble poor that rich people like to imagine. But he knows little of the Depression that plagues the nation his films are playing to. He figures the only solution is to hit the streets with a dime to his name, struggling until he’s “suffered enough” to make a movie about it. That’s an all-American thing to do. Mad Men just ended with this: Men will reappropriate anything—even and especially the culture of the lower classes—if it’ll provide an extra dollar in their pocket and another pat on their back.

So Sullivan finds his very own Arielle Holmes, in the form of Veronica Lake. She’s plays an actress who’s failed her way through the whole town, and runs into Sullivan on her way out of it. He asks her to buy him breakfast. She asks him for an introduction to Lubitsch. He counters that he just may be able to make that happen. She ends up seeing his mansion, realizing his profession, and tagging along as he tries to make nice with vagrants and hobos.

Sturges’ flights of verbal fancy are as close as the American cinema comes to Shakespeare, and his turns of phrase are as sharp as a shuriken. That’s reason enough to see his films early and often—without even mentioning his elegant visuals, or his master’s eye for slapstick. But for 20 minutes near the end of Sullivan’s, all that disappears. An audaciously dramatic sequence sees Sullivan cast out into the lower class without the help of his smartaleck beauty to talk him out of each complication. Travels is the one Sturges film remembered not for what its characters say to each other but for what it has to say: that any director who sets out to make hay of the lives of the downtrodden can’t possibly understand them. And that putting misery up on the screen in search of plaudits is the falsest thing any faux-artist can do.

What is it about Heaven Knows What that keeps us from leveling that charge its way? You hear the one-sentence description—”white middle-class directors put homeless girl and her friends onscreen, make their lives into melodrama, then go on to make their next movie about the diamond district”—and you write them off as tourists. They’re riding through the slums in a limo. But their movie doesn’t deny that. It works—it astounds, it wrenches, it becomes tragic poetry—precisely because they recognize it.

Heaven is startlingly honest about where these people would hang out—at McDonald’s, Starbucks, White Castle, Dunkin’ Donuts. Anywhere with affordable food, all-night hours, and a big enough bathroom to get high in. And we’re always looking at Harley and her friends from the outside in: They’re obscured by windows, by ads for iced coffee, or by more presentable patrons throwing shade their way. Even when they’re outside, they’re often concealed in long shots by the commuting masses, who walk by each frame not even caring to take note of the protagonists’ existence. The Safdies recognize the Sullivan in themselves, and build it into the very language of their movie that plays out from the perspective of a privileged outsider, who—at any moment—can choose to look away. Then the end credits roll, and we do.

HEAVEN KNOWS WHAT. RATED R. OPENS FRI 6.12. AT THE KENDALL SQUARE CINEMA, 355 BINNEY ST., CAMBRIDGE. FOR MORE INFORMATION, VISIT LANDMARKTHEATRES.COM/BOSTON/KENDALL-SQUARE-CINEMA

SULLIVAN’S TRAVELS. NOT RATED. MON 6.15 AT 7PM. COOLIDGE CORNER THEATRE, 290 HARVARD ST., BROOKLINE. FOR MORE INFORMATION, VISIT COOLIDGE.ORG .