The idea of a cinematic adaptation of a three-hour Tony- and Pulitzer Prize-winning play about a dysfunctional Midwestern family is likely to put some people's teeth on edge. While the thought of watching characters insult each other, scream, and reveal long-buried secrets may be anathema to some, for others -- especially those with an ear for Tracy Letts' particular brand of rhythmic dialogue and twisted familial relations -- John Wells' adaptation of August: Osage County is the perfect cocktail, albeit one with a lot of bitters. In easily the most impressive ensemble cast of 2013, Meryl Streep is the first among equals as Violet, the cancer-suffering, pain-med-addicted matriarch of the Weston clan, who loses her husband Beverly (Sam Shepard) in the movie's opening act. This prompts the return home of Violet's eldest daughter Barbara (Julia Roberts), along with her cheating husband Bill (Ewan McGregor) and their rebellious teenage daughter Jean (Abigail Breslin). Also arriving home for the memorial is Violet and Bev's youngest daughter, the impulsive Karen (Juliette Lewis), along with her skeevy, previously married fiancé Steve (Dermot Mulroney). They reunite with Ivy (Julianne Nicholson), the unmarried middle daughter who stayed close to home and has been caring for her parents. Rounding out the extensive family tree is Violet's loudmouthed -- and that's saying something in this clan -- sister Mattie Fae (Margo Martindale), Mattie's often stoned but decent husband Charles (Chris Cooper), and their bumbling adult son Little Charles (Benedict Cumberbatch), who has been carrying on a secret romance with Ivy. Lurking quietly in the background, making this ungrateful group food and putting up with Violet's racist asides, is Johanna (Misty Upham), a Native American housekeeper Bev hired just before he died. Detailing exactly how these people have caused each other such misery over the years spoils the fun of how deftly Letts, who also wrote the screenplay, has timed the revelations of the characters' backstories with the precision of a Swiss watchmaker. Just as we think we have a handle on why these people are acting the way they are, Letts unleashes another bit of the past, and as these facts surface you slowly begin to appreciate how fully he's thought through the characters. We stop looking for cause and effect, and just accept that these people are the way they are, warts and all. While that sounds somewhat defeatist or at least cynical, the dialogue pops with such biting humor, and the actors are all so remarkably skilled, that even with a cast this overstuffed nobody comes off as a caricature. No matter who is onscreen or what particular hell they are putting another character through, you can always savor the words and the performances. It's been said before, but it's worth repeating: Meryl Streep is the finest living American actress, and here she gets a part worthy of her protean skills. Violet is one of the most nightmarish screen matriarchs since Norman Bates' mom, but Streep makes her as realistically pitiful as she is monstrous. Margo Martindale and Chris Cooper are both flawless in each of their scenes, but they're especially fine with each other -- from their very first exchange, there's no question that their characters have been intimate for decades. Cooper gets the most heartfelt speech, one that articulates exactly how frustrated the audience feels with this supremely dysfunctional crew, and it's a showstopper in the best sense of the word. Wells' background in TV serves him well here. He doesn't try anything terribly flashy camera-wise and he makes no obvious efforts to "open up" the play other than to set a few scenes outside, yet he's expertly figured out how to give everybody in this cast a fair amount of screen time and still maintain the film's relatively lean and focused momentum thanks to the crisp and efficient editing. Like Days of Wine and Roses, Who's Afraid of Virginia Woolf?, Closer, and Doubt, August: Osage County proves that our definition of "cinematic" is often too restrictive. While film is obviously a visual storytelling medium, there's no denying that it's also one in which sound can have as much power as the pictures; for viewers whose favorite sounds include actors at the top of their game engaging each other with words that are playful, subtly poetic, and often spectacularly cruel, Letts and the cast give you an overabundance of moments to savor -- as well as the ability to be thankful you aren't a Weston. As Charles says to Mattie Fae at one point, you don't understand how these women can be so mean to the people they love, but as the closing credits roll over a dusty shot of the Oklahoma horizon, you'll appreciate how fully the movie has explored the ways in which a difficult life often makes people confuse and conflate cruelty and strength.