No one can turn the knife quite like family. That seems to be the central premise of the film adaptation of Tracy Letts’ Pulitzer Prize-winning play August: Osage County.

Whether you have survived a combative Thanksgiving family get-together, navigated the treacherous waters of a matriarch playing “who’s in the will/who’s out of the will” games, or discovered relatives colluding with perfect strangers to undermine some special accomplishment of yours, you will find something to which you can relate in this caustic, fractious, anarchic dramedy.

(Hey, I’m not saying the terrible things detailed above have happened to me and mine … oh, wait, who am I kidding? Of course they have.)

The film is like an episode of Carol Burnett’s/Vicki Lawrence’s old sitcom Mama’s Family … if it had been co-written by Eugene O’Neill, David Mamet and Tennessee Williams … with directorial consultation by Ryan Murphy and David Fincher. The story is a bleak one with Sam Shepard, playing an alcoholic Sooner poet whose sell-by date has long expired, committing suicide and setting off a whole raft of fireworks as his drug-addled, cancer-stricken, chain-smoking widow (portrayed by Meryl Streep) tears through her assembled family of grieving ingrates and dopes.

Streep is a hoot, throwing vanity to the wind and not once making the critical error of having contempt for her spiky character Violet. She is authentic through and through, calcified by years of disappointment, betrayals, and brutality (both genuine and mythologized).

Julia Roberts as bossypants daughter Barb is Streep’s match, their scenes together crackling with sympathetic ugliness. I lost any affinity for Roberts ages ago, but it came back in spades while watching this entry in her illustrious career. She wrings comic gold from the sympathy/revulsion/love/hate she feels for her family, which also includes the very good Julianne Nicholson and the disappointingly so-so Juliette Lewis as her two sisters Ivy and Karen as well as a heartbreaking Benedict Cumberbatch as their cousin Little Charlie.

Rounding out this star-studded cast are Chris Cooper and Margo Martindale as Charlie’s parents and the three sisters’ uncle and aunt. Martindale plays Streep’s wry, equally embattled sister Mattie Fae. These two are so good and so believable, beautifully centering the proceedings which often threaten to spin off into absurd melodrama.

Less effective are Ewan McGregor as Roberts’ yuppified, simpering husband or Dermot Mulroney as Lewis’ yuppified, slime-bucket fiance. Their respective performances are phoned in and dull, lost in the nigh-operatic ACTING! cacophony generated by their fellow cast members.

Little Miss Sunshine‘s Abigail Breslin is rather pedestrian as the daughter of Roberts and McGregor, rising to the fore only once when she delivers a deeply-felt monologue about the “fear we eat” when we consume animals. Her character is a vegetarian, and the monologue, imparted to her family at the post-funeral dinner table, clearly is a metaphor for the vicious consumption her relatives do of each others’ souls. And the fact that they all behave like jackals, immediately ridiculing the young girl’s beliefs, compounds the imagery.

I haven’t seen the stage version upon which this film is based, nor have I read it, so I can’t play the pretentious “I saw it on Broadway and I know how it is supposed to be performed so the movie sucks” card. I do suspect, however, that the film struggles, as so many adaptations do, expanding upon the insular, claustrophobic, sweaty envelope that the stage experience can so brilliantly create for an audience. Do you keep these characters trapped around the dinner table, or do you have them cavorting all about Oklahoma?

Director John Wells, who has worked primarily in television, has a workmanlike approach that doesn’t do much to open up the material, but wisely he just gets the heck out of the actors’ way and lets them do their scenery-chomping thing.

I will also suggest – and this is a criticism of the script and its source material (both written by Letts) – that the third act suffers from some over-baked, soap opera twists that I found rather silly. These plot points do set up a zinger of a scene with Roberts and Streep and some ill-fated plates of catfish, but overall they left me scratching my head a bit. Ah well.

As relentlessly dark as this material is, the film is fun and mostly moves at a brisk pace. I don’t know how well the years will treat it. I suspect it won’t age well and eventually will seem like a quirky exercise in pulpy camp. However, in its moment with most of its cast at the peak of their powers, it’s worth checking out … and probably cheaper than two hours of therapy.