If you're ever in a position where you feel like your entire family has gone insane, and you're unfortunately related to some of the worst people on the planet, then August: Osage County is here to give you a little perspective. Unless your surname happens to be Hitler, then no matter how demented you believe your relatives to be, they're always going to come in second in the Dysfunction Olympics to the Weston clan.

When noted poet and chronic alcoholic Beverly Weston (Sam Shephard) goes missing, leaving behind his wife Violet (Meryl Streep) who's sick with cancer, the entire family reconvenes in the sweltering home to look for him. Returning to the house that unhappiness built, we have the embittered Barbara (Julia Roberts), her estranged husband Bill (Ewan McGregor) and their rebellious teenage daughter Jean (Abigail Breslin); there's loved-up and naïve Karen (Juliette Lewis) and her new fiancé Steve (Dermot Mulroney); Violet's secret-hoarding sister Mattie Fae (Margo Martindale), her consta-high husband Charlie (Chris Cooper) and their awkward son Little Charlie (Benedict Cumberbatch). Also in the mix are Ivy (Julianne Nicholson), the one daughter who stayed behind with the family, and Johnna (Misty Upham), the live-in nurse that Beverly hired right before he disappeared. With this many people and so much history under one roof, it's not long before dark truths and buried secrets are hurled about the place like emotional weaponry.

Based on a play by Tracy Letts (Killer Joe), and directed by Wells who is mostly known for TV work, August never quite escapes its theatrical origins. Characters are prone to speaking in long, personal details-filled monologues, with most of the action taking place in one house.

Which isn't to say that the "action" isn't great. Slowly building up a 25-minute dinner scene that vaults from hilarious to horrific and back again, this is very much an Actor's Movie, for better or worse. Streep is as fantastic as ever, Roberts gives one of her best and most vital performances in a decade, and the majority of the rest of the line-up - bar an out of place McGregor and a miscast Cumberbatch - take great relish in sinking their teeth into these meaty roles.

Once the dinner scene comes to an end however, the rest of the movie is barely propped up by soap-opera plot twists and a realistic but anticlimactic ending.

An example of a fantastic cast outperforming the movie they're in, August: Osage County is a bit like listening to your neighbours arguing. Entertaining, yes, but there's also something intrinsically wrong and unenjoyable about it, too.