Producers are wise to be wary of scribes who want to direct their own plays — unless that scribe happens to be Athol Fugard. The South African playwright, director, actor, and political activist (who turns 80 this year) is Signature Theater’s current playwright in residence and the sure-handed director of “Blood Knot,” his ground-breaking play about two half-brothers living under the de-humanizing legacy of apartheid. A smart choice for the company’s inaugural production in its new home, the 1961 drama is both a sobering theatrical experience and a sharp reminder of the company mission.

Acoustics and sightlines are top-shelf in the aptly named Jewel Box Theater, one of three performance venues in the new Signature Center designed by Frank Gehry. Even better, the space makes the auditorium of the compact 191-seat house feel roomy.

Onstage, that expansive feeling gives way to claustrophobia on Christopher H. Barreca’s set of the wretched hovel where half-brothers Morris (Scott Shepherd) and Zachariah (Colman Domingo) live in poverty in the “non-white” section of Port Elizabeth. Everything in this mean shack looks like salvaged goods, from the knocked-together walls to the makeshift kitchen-in-a-cupboard where white-skinned Morris fixes meals for his dark-skinned brother, who supports them both through menial work.

Morris is the brother with the words. The one who can read and write and who supplies Zach with the words — “prejudice,” “injustice,” “inhumanity” — that he needs to describe the way his white boss treats him. Shepherd, a Wooster Group stalwart, has a way with Morris’s words, but an even more uncanny way with the body language of someone who talks to conceal his private thoughts.

Zach is the physical brother, the one whose hunger for love and laughter can’t be satisfied with words. In his exhilarating performance, Domingo (“The Scottsboro Boys”) allows Zach to grow and grow until he fills the room with his mercurial passions. But once he finds his own words to challenge his brother, the scent of violence is sulfuric.

Fugard the director conveys the stifling closeness of the brothers’ relationship through the domestic rituals they observe. Every movement is deliberately measured and paced so it doesn’t upset the balance of power in this confined space.

Fugard the playwright, however, makes sure the balance does shift, and radically so, when Zach demands a woman and Morris humors him by initiating what he assumes is a harmless pen-pal correspondence with a woman from another town. But when the woman turns out to be white — and is prepared to make a visit — the unspoken racial tensions between the two brothers break loose and run wild.

It’s easy to see why the play was banned in South Africa after the single performance given in 1961 with Zakes Mokae as Zachariah and Fugard himself playing Morris. But it’s nothing short of astonishing to realize how potent — and how painful — the racial issues still are today.

Blood Knot

Alice Griffin Jewel Box Theater; 191 seats; $25 top

  • Production: A Signature Theater presentation of a play in two acts written and directed by Athol Fugard.
  • Crew: Set, Christopher H. Barreca; costumes, Susan Hilferty; lighting, Stephen Strawbridge; sound, Brett Jarvis; original music, Doug Wieselman; dialect coach, Barbara Rubin; fight director, Rick Sordelet; production stage manager, Pamela Salling. Opened Feb. 16, 2012. Reviewed Feb. 14. Running time: TWO HOURS, 30 MIN.
  • Cast: Morris - Scott Shepherd <br> Zachariah - Colman Domingo