Don’t mistake the lobby poster for “Ben Is Back” — an image of a wayward teenager hugging his mother — to mean this will be an upbeat holiday tale. And don’t assume the status of the actors in that photo — superstar Julia Roberts and next big thing Lucas Hedges — indicates a big-budget epic.

On the contrary, this is an intimate, incredibly tense drama about a troubled family battling raw emotional pains, a bare-bones and bare-knuckled look at the destructive powers of addiction.

The title character (Hedges, who’s everywhere these days, including “Boy Erased” and “Mid90s”) is a drug addict who has taken a leave from his treatment program to come home for Christmas. His arrival is a surprise — and not a universally well-received one.

His mother, Holly (Roberts), struggles to put a happy spin on the visit. She forces a smile and embraces Ben in a long hug — then, the instant he’s distracted by the rest of the family, rushes around the house scooping the drugs out of the medicine cabinet and hiding her jewelry. Once everything is secure, she reassumes her pained smile and tries to assure everyone — including herself — that, with Ben back, the family is going to have a warm holiday celebration, just like they used to.

The two youngest members of the family are grade-schoolers too small to understand why Ben has been gone but thrilled that he’s back. But Ben’s teenage sister, Ivy (Kathryn Newton), makes no secret of her anger over the misery he inflicted upon the family (the details of which are gradually revealed). And his stepfather, Neal (Courtney B. Vance), while wanting to support Holly’s vision of a Hallmark-card holiday, clearly doesn’t trust Ben or his motives for the unannounced visit.

Ben understands the mixed reaction. In fact, he’s wrestling with the same issues, at one point admitting that coming home for Christmas might have been a wonderful idea or the biggest mistake he’s ever made. And he’s made some really big mistakes.

The movie was written and directed by Peter Hedges (Lucas’ father), an Oscar nominee for best adapted screenplay for 2002’s “About a Boy.”

The story takes place in a small town. Everywhere Ben looks, he sees something that triggers a bad memory. When Holly drives him to the mall to shop, she notices him staring at one of the houses they pass and asks him why. “I robbed it,” he says softly.

The discomfort in that scene is nothing compared with the anxiety when Ben enters church for Christmas Eve services and encounters the mother of a friend who died from an overdose while they were getting high. Ben OD’d that night, too, but survived.

Roberts and Hedges dominate the screen time. Hyperventilating her way through a series of crises — Roberts is really good at making the veins in her forehead stick out — the actress could have dialed down the scenery-chewing a notch. She might have taken a lesson from Hedges, an Oscar nominee for “Manchester by the Sea,” who shines in an understated performance as Ben wars with his inner demons.

The elder Hodges deserves kudos for casting an interracial couple — and then never making that any sort of a factor.

The closest we come to Ben showing any ill will toward his stepfather is when he calls Neal a nerd. Holly doesn’t deny it, reminding him, “It’s because he’s a nerd that we can afford to send you to treatment.”

Peter Hedges also demonstrates a non-egotistical touch. Many directors who do something clever can’t resist drawing attention to it. He slips meaningful little asides into out-of-the-way places.

Shortly after Neal and Holly argue over Ben’s arrival, there’s a scene focusing on Ben’s interaction with his young siblings where, without fanfare in one corner of the background, the couple exchange a quick makeup hug.

If only all their problems were that easy to solve.

“BEN IS BACK”

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(R, 1:43)