Erica Chamblee and Chris Genebach in Mosaic Theater Company’s production of “A Human Being Died That Night.” (C. Stanley Photography)
Theater critic

You want to try acting a whole show with your feet chained to the floor? Chris Genebach accomplishes it with flair as South Africa’s notorious Eugene de Kock, the apartheid-era Death Squad officer widely known as “Prime Evil.” The white de Kock wisecracks about a Hannibal Lecter vibe as he sits on the other side of a prison cell interrogation table from a black woman, Pumla ­Gobodo-Madikizela, but the 80-minute “A Human Being Died That Night” is anything but a psycho-thriller. It’s an unflinching face-to-face dialogue about how people and countries become utterly unglued.

Nicholas Wright’s script is based on the 2003 book by ­Gobodo-Madikizela, a research professor who worked with South Africa’s Truth and Reconciliation Commission in the 1990s. The theatrical challenge is to make compelling drama of interviews stuck in one room, but Logan Vaughn’s composed production for the District’s Mosaic Theater Company makes no bones about its source of electricity. It’s de Kock. How did he show up for work each day ready to murder?

In Genebach’s riveting performance, information gushes forth in torrents. Erica Chamblee’s diplomatic but dogged ­Gobodo-Madikizela presses de Kock for details: Who was targeted by the squads? What were the methods of torture and execution? The facts are harsh, and as Genebach’s de Kock zips through the complicated incidents you begin to see him as a single, efficient piece of a vast, warped cultural-political machine.

Yet he’s weirdly personable, and this is where Vaughn’s production rises to the artistic level of its repertory mate this month at Mosaic, Joy Zinoman’s exemplary staging of Athol Fugard’s 1961 “Blood Knot” (like “A Human Being,” it is acted with rich South African pronunciations). “Blood Knot” watches brothers ripped apart by the social ­convention of race; Gobodo-Madikizela’s project, on the other hand, examines whether forgiveness is possible under such extreme conditions as those South Africa suffered, which is why she sought out no less a “monster” than de Kock for her interviews. There is a moment when her hand grazes de Kock’s on the table, and it’s a fleeting shocker. Chamblee and Genebach measure such rare displays expertly: the tone of Vaughn’s production is never remotely sensationalistic or sentimental.

It’s clinical, and grippingly inquisitive. The show opens with slides projected behind the bars of Debra Booth’s constricted set (the design team is the same as for the similarly focused “Blood Knot”), and though Michael Giannitti’s lights subtly bump up and down as the interviews unspool, the dynamics are almost entirely in the hands of the actors.

Chamblee deftly keeps reframing the discussion as the ­empathetic, rigorous Gobodo-Madikizela, but naturally the bulk of the interest falls on de Kock. Chained in place and garbed in an orange prison jump suit, Genebach still finds plenty to work with in de Kock’s grim tales, which he tells vividly but without undue embellishment. As Genebach plays de Kock — quick mind, impulsive responses that seems guileless — the man seems direct, frank, on the level. You wonder: Is he for real? Can you trust him?

The dialogue is loaded with grotesque incident, murky motivation and, eventually, sincere emotion. This would be wrecked by overplaying, yet the performance never stumbles. Simply from an acting point of view, this “South Africa: Then & Now” rep establishes a new high bar for Mosaic. And deep into the troupe’s second season, you can feel the dividends accumulating as this social-justice-oriented company finds lens after lens, from local to international, magnifying humanity’s sharp sociopolitical divisions . . . and maybe, as the persistent Gobodo-Madikizela hopes, somehow softening even unforgivable crimes and the failures that seem most profoundly irresolvable.

A Human Being Died That Night, by Nicholas Wright, based on the book by Pumla Gobodo-Madikizela. Directed by Logan Vaughn. With Jason B. McIntosh. Costumes, Brandee Mathies; composer, Mongezi Ntaka; sound design, David Lamont Wilson; projections, Patrick Lord. About 80 minutes. Through April 30 at the Atlas Performing Arts Center, 1333 H St. NE. Tickets $40-$60. Call 202-399-7993 or visit mosaictheater.org.