NEW YORK - I don't care if

August: Osage County

is 31/2 hours long. I wanted more.

I'm not sure what grew on me most: the fictional Weston family - dysfunctional, for them, is a feeble adjective - or the galvanizing acting by a troupe that pares every role down to its sinews, or playwright Tracy Letts' way of making a simple interchange scary and hilarious, at once.

Letts' new play opened last night on Broadway, in a sterling production by Chicago's Steppenwolf Theatre Company. His characters get their hooks into each other and rip, rip, rip - the deeper the gashes the more rewarding for the audience. August: Osage County is like watching blood sport, except that the wounds are intellectually induced.

Letts doesn't exactly hit the ground running. His initial scene seems a little long, as we meet the patriarch of this clan, a retired poet/professor who has a deal with his wife, Violet: She leaves him alone about hitting the bottle, he lets her pop her fantastic collection of pills in peace.

The minute Violet comes down the long staircase of Todd Rosenthal's stage-high, three-story set, you know you've met a classically charged planetary force - and August lifts off. It never really touches back down, even if the Weston family itself spends the next three hours crashing all over the place.

Papa has just hired a feet-on-the-ground American Indian woman named Johnna to help take care of Violet in their sprawling house in No-wheresville, Okla. Then, the next morning, he disappears.

This brings everyone into the crisis. Ivy is immediately on the scene; she's the middle daughter, living in town and feeling responsible for looking after her parents - even as her mother constantly pecks her apart.

Into the house comes Barbara, the eldest daughter, still feeling the sin of leaving town. She's with her husband and pothead kid. After that, Karen, the youngest, shows up with the man she's going to marry; she's strayed so far from the family, she's almost estranged.

Throw in an uncle, a marvelously mouthy aunt, plus the lumpy adult son she's berated into mush, and it's enough to befuddle even the sheriff who's trying to find the missing patriarch.

All the old family patterns emerge - often extreme versions of everyday family interchanges you've been through when a cousin displays a particular trait or a sibling opens an old mental wound. Letts calls his three-act play a drama, but he's written an industrial-strength black comedy, wickedly funny and unsettling.

Anna D. Shapiro has directed August with a passion for in-your-face storytelling. Deanna Dunagan, as the pill-addicted doyenne, looks like an elder Jane Wyman and is a dynamo in the role - equally dangerous when she's playing lucid or not. All three actors portraying the daughters - Amy Morton, Sally Murphy and Mariann Mayberry - nail their characters; Morton, as the oldest, gives a performance so visceral, you can almost hear her screaming inside.

The rest of the cast, particularly Rondi Reed as the aunt who lost her social filter, is fully up to the task. When they all come together at the end of Act 2 for a wild dinner scene - the most memorable of several pieces of the play - you'll see ensemble acting, fueled by precision writing, that comes at you with hurricane force. Dress properly.

August: Osage County

Written by Tracy Letts, directed by Anna D. Shapiro, set by Todd Rosenthal, costumes by Ana Kuzmanic, lighting by Ann G. Wrightson, sound by Richard Woodbury. A production of Steppenwolf Theatre Company, Chicago.

The cast: Deanna Dunagan (Violet Weston), Amy Morton (Barbara), Sally Murphy (Ivy), Mariann Mayberry (Karen), Rondi Reed (Aunt Mattie Fae), Francis Guinan (Uncle Charlie), Ian Barford (Little Charles), Kimberly Guerrero (Johnna), Jeff Perry (Bill), Madeleine Martin (Jean), Brian Kerwin (Steve), Dennis Letts (Beverly Weston), Troy West (sheriff).

Playing at the Imperial Theatre, 249 W. 45th St., New York. Tickets: $26.50-$99.50. Information: 1-800-432-7250 or www.augustonbroadway.com.EndText

Contact staff writer Howard Shapiro at 215-854-5727 or hshapiro@phillynews.com.