A look at the lives of the strong-willed women of the Weston family, whose paths have diverged until a family crisis brings them back to the Oklahoma house they grew up in, and to the dysfunctional woman who raised them.

Holiday ham.

It must have looked good on paper: Meryl Streep as the bitter, paranoid, pill-popping matriarch Violet Weston; Julia Roberts as Violet’s control-freak eldest daughter Barbara; Ewan McGregor as Barbara’s philandering husband Bill; the always-dependable Chris Cooper as Violet’s sister’s husband Charlie, the lone voice of reason in the clan; and the currently ubiquitous Benedict Cumberbatch as Charlie’s clumsy yet beloved son.

Streep and Roberts rage and clash, but never manage to inhabit their parts.

But then, something funny happened on the way to realising the long-gestating film version of Tracy Letts’ acclaimed play August: Osage County. Almost as if the producers ran out of money, they then hired the likes of Dermot Mulroney and Juliette Lewis to round out the cast. The resulting film, being pushed hard for awards-season recognition, is an over-baked ham of an adaptation that succumbs to third-balcony histrionics and a cop-out ending (which won’t be revealed here, but can be read about extensively via an online search).

To briefly summarise the plot, after hiring a live-in Native American caregiver (Misty Upham) to care for the dangerously unhinged and cancer-stricken Violet, her husband Beverly (Sam Shepard) disappears. This prompts an impromptu reunion of the Weston clan, which includes Barbara, Bill and their teenaged daughter Jean (Abigail Breslin), Barbara’s Forida-based sibling Karen (Lewis) and her current boyfriend (Mulroney), live-in sister Ivy (Julianne Nicholson), Violet’s outgoing but cruel sister Mattie Fae (Margo Martindale) and her husband (Cooper) and son (Cumberbatch).

Each of these people has a secret to hide and an axe to grind. When it is discovered Beverly has taken his own life, the grief added to the mix is enough to boil the mixture over.

To his credit, Letts’ adaptation of his play opens things up enough to give the viewer a strong sense of place. The wide open spaces of eastern Oklahoma dwarf the Weston hot-house of anger and pain, framing the petty family bickering in a way the theatre is incapable of doing. Scenes that were set in the lounge, dining room or various corners of the large house are now distributed around the grounds. This allows the intensity and tensions to breathe a bit, which is a good thing.

Yet the enterprise is undone by the gulf in the talent. Streep and Roberts rage and clash, but never manage to inhabit their parts. So when their inevitable physical confrontation comes, viewers are left to marvel at the site of the two actresses wrestling with each other and not their characters. Cooper, Martindale and Nicholson acquit themselves the best, though the less said about Mulroney and Lewis, the better.

Casting aside, the choice of John Wells as director probably also looked good on paper but is equally problematic. A producer, writer and show-runner who cut his teeth on such American dramas as China Beach, ER (George Clooney is a producer of the film) and Third Watch, his experience with ensembles in close quarters is established. Yet in his second feature film following The Company Men in 2010, his rhythm seems off and the energy level ebbs and flows. In the end, the Westons seem like a family of strangers, their petty problems and indignities unworthy of time or attention.