One problem with iron-willed matriarchs that they are seldom guided by altruism. That is not the case with the Mattie Cheeks of John Henry Redwood’s suspenseful race drama No Niggers, No Jews, No Dogs, which won the 2001 Barrymore Award. She sacrifices her self-respect to the cause of family cohesion, and she comes off all the stronger for it in this terrific production at New Repertory Theatre.

Mattie is a washerwoman living with husband Rawl and two daughters, bookish Joyce and playful Matoka, in a tarpaper shack in the piny woods of Halifax, North Carolina, in 1949. Although times are tough, the family are content, and there’s always enough food to make up dinner baskets for Mattie’s mysterious Aunt Cora, who wears mourning clothes and communicates by humming hymns.

The interloper is Yaveni Aaronsohn, a yarmulke-wearing self-styled anthropologist who’s doing " a comparative study of the similarities in racial suffering between negroes and Jews, " with special attention to the signs denoting segregation. ( " No Niggers, No Jews, No Dogs " refers to a billboard in Mississippi). But he’s a red herring — the real drama comes after Rawl departs for Cleveland to do a short-term job, leaving the womenfolk on their own, and they fall victim to a crime that’s both unspeakable and absolutely ordinary in the context of Halifax.

What should Mattie do? She’s well versed in the ways of the South, a world in which blacks are the underdogs and black women the lowest of all. She knows that telling (white) authorities is apt to bring even more dire consequences, especially if a black man leaps to the defense of the clan. Too often, the results can be what Billie Holiday described as " strange fruit. "

In No Niggers, Yaveni isn’t the only outsider appalled at the inner workings of this place — he represents every audience member who’s aghast at Mattie’s outrageous yet ultimately family-preserving passivity. Although some plot turns are telegraphed, Redwood’s drama is enthralling, and the New Rep production is well polished. Janie E. Howland’s outdoor set includes the porch, shack, and water pump; Molly Trainer’s costumes are in period patterns and styles (she uses the same material for apron and frock). Joseph C. Fox has designed a versatile lighting scheme that indicates any time from dawn to dusk to deep into the night.

Director Adam Zahler shows enormous sensitivity to family dynamics. The Cheeks girls squabble good-naturedly, yet a word from their parents always puts them back in line. Redwood has written a leisurely show that clocks in at nearly three hours, so we really get to know them. Natanjah Driscoll’s 11-year-old Matoka is frisky and sly; Giselle Jones’s teenage Joyce is a barefoot scholar reading Homer’s Iliad. Joyce is so emboldened by her family, she believes her father can do anything, but in this world, that’s a dangerous presumption. Jones is excellent at vacillating between childish naïveté and dawning adult knowledge. Unfortunately, Ted Kazanoff as Yaveni strikes a false note. In part the play’s structure is to blame: only at the end do we get to hear Yaveni’s involved backstory, which includes first his rejection and then his belated embrace of his Jewish roots. The monologue is long and overelaborated, and by the time Yaveni delivers it, you’re already wrapped up in the Cheeks family.

Jacqueline Gregg and Baron Kelly as Mattie and Rawl are dazzling. Kelly is powerfully built, and he uses the whole stage to roughhouse with his daughters. With his wife, he makes that playing space as intimate as a bedchamber. Gregg pulls off something rare and fine on stage: through subtle changes of voice and bodywork, she shows how Mattie grows and changes. These two characters generate real heat, and during the second act, when they sit on the porch to try to come to terms with the damage that’s been done, Mattie clings to Rawl as if he were a life raft in perilous seas. It’s a heartbreaker.