“We find the words for what cannot be described,” says Duma Kumalo in the Yale Cabaret’s newest show, “He Left Quietly,” directed by Leora Morris DRA ’16. The words are “shit” and “blood.” The words are “noose” and “coffin.” And all of these are punchy, sure, but inadequate. Genocide is senseless and impenetrable. Our causal chains and linguistic nets will never fully capture slaughter. Who can explain why thousands were killed, abused and tortured? Playwright Yaël Farber doesn’t ignore the gap between word and reality. She studies it closely. “How to arrange the unarrangeable, order what is shattered?” her character asks, palms up, as if in surrender.

Of course, Farber first establishes a semblance of order, a simple, skeletal narrative she later deconstructs. She tells the true, harrowing tale of Duma Joshua Kumalo, a black South African accused of murder following the 1984 riots in Sharpeville. Though he is innocent, not even a witness to the mayor’s death, Kumalo is condemned under the law of common purpose. (Because he rioted alongside the murderer, he is equally responsible.) He spends the next four years in prison, awaiting the gallows. The play unfolds and unwinds in a chronological limbo, swaying between the 80s and early 2000s, when Farber and Kumalo first meet. The older Kumalo, played by Yahya Abdul-Mateen II DRA ’15, sits downstage with a suitcase at his side, while his younger self, played by Ato Blankson-Wood DRA ’15, acts out the unsettling memories — nights spent talking to himself or sobbing hysterically. Hovering nearby, Farber’s character, played by Maura Hooper, gives the play its momentum. She prods Kumalo when the story slows and occasionally offers the audience inspirational takeaways.

But Kumalo avoids generalities — instead, he gives us anecdotes so vivid they’re almost nauseating. In those moments, moments of claustrophobic intimacy, the play feels not only tragic but true. Kumalo admits that he extracted his own teeth. He pulls back his cheek to expose the gaps and says, “A trip to the dentist meant if I looked out the car window, I could see the sky.” Farber recoils and gasps. The audience recoils and gasps. Still, he is unashamed. He goes on to explain how prisoners communicate — they dry out their toilet bowls and whisper into the pipes. The plumbing, he says, is full of “secrets and shit.”

When the script sinks to platitude, however, “He Left Quietly” becomes just another preachy war story. Breaking the fourth wall, Farber turns to the audience and pontificates, questioning the very nature of liability. Under the law of common purpose, who is to blame for the Apartheid? Who is to blame for all the bloodshed? Farber’s musings sound both simplistic and self-important — these are questions better left unsaid. And the final scene, which has cast and audience members sorting a pile of dead men’s shoes with reverence, feels like a gimmick. A successful war story is a detailed one, not a numbered list or a metaphor or an ethical debate.

Yet the three actors bring the requisite complexity and depth to an imperfect script. Hooper can look apalled, listening to Kumalo’s story, and suddenly vicious, when she doubles as a prison guard. And with his sonorous voice and leisurely delivery, Abdul-Mateen is the perfect narrator and focal point. He makes deliberate eye contact with the audience and delivers choice phrases with a wry smile. Recalling his last meal, a boneless chicken, he pauses. “I ate that fucking chicken,” he adds. And Blankson-Wood is no puppet: In reenacting Kumalo’s past, he has energy and grace. He screams and tears at the metal gate upstage with astonishing ferocity, the brute, theatrical force that jolts a sleepy audience awake.

“He Left Quietly” is savage, so honest and bloody you’ll sometimes want to turn away and examine your fingernails instead. Even the spare set and shaky projections on the back wall are painful. But, as the lights first go up, Kumalo asks: “If the truth falls on empty chairs, does it make a sound?” At the Cabaret this weekend, the chairs will not be empty, and the truth will not fall silent.

JANE BALKOSKI