We've all been to those plays -- the ones that sneak up after intermission and suddenly explode in a gripping dramatic scenario that stabs you in the heart. Playwright Carlyle Brown has managed that dynamic in "American Family," a world premiere that opened Friday at Park Square Theatre in St. Paul. Directed by Marion McClinton, the drama takes time to lay down an expository first act and then zeroes in with a focused intensity on a singular and fraught relationship.

Tracey Maloney plays a woman, Mary Ellen, who has returned to her hometown after a long absence. The manner in which she left her family at age 10 has damaged her life with profound consequences. Maloney's sad eyes and mournful tone perfectly convey the sagging weight of life on her shoulders. But there remains a spirit of recognition in her for the happiness that once existed in her life, and the very fact that she hopes to reach out to a brother she has never seen says something about the familial tug within her.

Michael Terrell Brown is Tommy Richardson, Mary Ellen's 16-year-old half brother. The last time Mary Ellen saw him, he was "just a lump on mama's belly." Tommy has the appearance of a good kid, athletic and clean-cut. But just as Mary Ellen has spent 16-plus years living with the void of not knowing her brother, so too Tommy has lived in a house where his sister's absence has damaged everyone. Every year at Mary Ellen's birthday, her absence had created almost a myth that he had to combat. Brown flashes with a hot temper, and scowls as he skeptically questions his sister's motives in returning home.

Playwright Brown has draped this complex and aching story in one of the myriad racial injustices of the old South. When the play opens, Maloney's character (described as the narrator) comes upon her 9-year-old self in 1964. Young Mary Ellen is played by Megan Fischer with a lovely sense of liveliness, honest hope and goodness -- her fragile optimism wrapped around a flinty good spirit. Her mother, Laura (Noël Raymond), who is white and long divorced, is about to marry African-American Jimmy (Gavin Lawrence). Mixed-race marriage was illegal in Alabama in 1964, and this is the dramatic trigger Brown uses to unfold his plot.

The first act struggles to get past the formulaic taste of an after-school special. Laura, Mary Ellen and Jimmy go to live with Jimmy's parents, who initially resist the intrusion of a white woman and her daughter, but come to love them. But the act closes with palpable agony as Fischer's Mary Ellen, in all her gawky vulnerability, is forced to leave her now-pregnant mother and the only family she has known.

McClinton then attacks the brisk rhythms in Brown's crackling second act -- an emotionally raw examination of the hole that exists in both Mary Ellen and Tommy. As is his style, McClinton refuses to let sentiment muddle the anger's toughness. Brown has written for Maloney a character whose wound is so deep that she herself doesn't understand it. McClinton draws out the confusion and rage in both her and Michael Terrell Brown's Tommy. By show's end, we could scarcely care more for two people.