It’s not the editor, but the editing strategy that undermines “Beautiful Boy.”

This sensitive retelling of the true story of journalist David Sheff and his son Nic, a drug addict whose crystal meth mania became two books — one written by the father, the other by his aspiring-writer/recovering addict son. Those dual narratives might account for the film’s choppy, disjointed feel and flow, a powerful and almost certainly compelling and intimate drama about parenting, personal responsibility and the shock waves that spread from one addict through an entire extended family.

Rarely has a film with alleged Oscar pretensions felt more “meh.” Sympathies are undercut, “big moments” are countered with off-key ones and suspense is frittered away like an addict’s college fund in this, the most scenic movie ever made on this subject.

Steve Carell is David, an indulgent dad given to singing John Lennon’s “Beautiful Boy” to son Nic from an early age. Nicolas was the son of his first marriage (brittle Amy Ryan is the first wife) who turns out to be the best older stepbrother ever when Dad’s remarriage (earthier Maura Tierney plays Karen, an artist) produces two moppets whom Nic (Timothée Chalamet) dotes on like puppies Dad just brought home.

Nic’s dad writes for Rolling Stone (among other publications), so the kid has access to all the best music and an affluent lifestyle in the most beautiful part of coastal California. But Dad tilts towards “Your best pal” in his parenting. “Let’s go surfing!” Let’s bang our heads to Massive Attack!

And then the kid counters with, “Let’s smoke this joint together, Dad.”

Nothing to worry about, right? We’re not still selling that “gateway drug” thing, are we? Not in San Francisco. Not at Rolling Stone!

“It takes the edge off stupid reality,” Nic says. Uh-oh.

As Flemish filmmaker Felix van Groeningen’s film skips back and forth through flashbacks and a floating fictive present that’s not a straight-forward narrative, we see David remember these moments and read into them the second-guessing that has to come with it.

The sweet kid is in rehab at 18 with a veritable cornucopia in his veins. We know now what David and Nic did not. That 28 days is not enough to break the meth habit.

We share David’s utter contempt for the rehab folks who excuse this failure with “Rehab is part of the recovery.” But being a journalist, David snoops around Nic’s room, his journals, and picks up clues. He buys a meal for another addict on the street to get a sense of the allure and consults with an expert (Timothy Hutton) who thinks he’s being interviewed for The New York Times Magazine, an expert who points out the deadly chemistry that makes meth so hard to shake.

Chalamet (“Call Me By Your Name”) is the very picture of mercurial in this part, gushing with enthusiasm and sweetness with his step-siblings one moment, lying, cheating stealing and relapsing the next. He’s got the guilty face of a student using the school library computer to look up “How to shoot up safely,” and the amorality of a junkie who thinks nothing of helping his college girlfriend (Kaitlyn Dever) learn to cook and shoot up, and then overdose. Chalamet manages a stoned-manic swagger as he insists on being “on my own” in his teens, and cadges cash to sustain his death spiral.

Tierney and Ryan play interesting “mother” contrasts and have some of the best scenes in the movie. Karen has to protect her own children, but something else kicks in when Nic and the girlfriend flee their house. She chases them down, weeping. Ex-wife Vicki (Ryan) didn’t get custody, but seems like Nic’s LA lifeline when the chips are down. If only she could break off the same fight she and David have been having for years.

Carell has the biggest part and he gives a most uneven performance in it. His David is a rational man more inclined to lose his temper over Nic’s evasions and others’ failure to watch the addict like a hawk. Carell’s emotional meltdowns seem forced and tepid and remind us we’ve never really seen him master that.

Only small pieces of the rehab experience seem novel here. I’d never heard of “The Three Cs” before — “I didn’t cause it. I can’t control it. I cannot cure it.” All part of that surrendering to a higher power thing, and letting yourself off the hook just enough to get better.

But when Nic jots in his journal about the shame his drug use causes him and how he uses more drugs to forget the shame, you have to think, “Yeah, it’s like that.”

Director/co-writer van Groeningen (“The Broken Circle Breakdown”) is out of his depth (that choppy editing) and treats this production like a Belgian kid at the Hollywood Buffet. The soundtrack is so littered with (pricey rights) songs you can tell he’s spending Other People’s Money, and some are so on the nose (Neil Young’s “Heart of Gold,” Perry Como covering “Sunrise, Sunset”) that they make you wince.

But it’s the cutting that undercuts this son’s journey through addiction and his father’s all-but-helpless response to it. The wind goes out of the movie’s narrative moment and the air leaves the balloon of Chalamet and Carell’s performances which we watch deflate as we lose too much of our sympathy for their story.

MPAA Rating: R for drug content throughout, language, and brief sexual material

Cast: Timothée Chalamet, Steve Carell, Maura Tierney, Amy Ryan

Credits:Directed by Felix van Groeningen, script by Luke Davies and Felix van Groeningen, based on books by David Sheff and Nic Sheff. An Amazon Studios release.

Running time: 2:00