Antony Sher speaks the words of Primo Levi in a slightly incredulous tone, almost as though the events at Auschwitz are so unfathomable they can't be summoned with anything but astonishment even by those who lived through them. We're familiar going in, if not with every particular of Levi's experience, then with the horrors in broad outline: the boxcar rides, the delousing, the ovens, the starvation, the beatings, the subhuman housing, the stripping away of what it is to be you, to be a civilized person.

This last feature of the Nazi obscenity seems to be at the marrow of "Primo," Sher's one-man show based on Levi's widely admired 1947 death camp memoir, "If This Is a Man." In the 90-minute production at the Music Box Theatre, the South African-born actor, long a British subject, does not so much impersonate Levi as offer himself as a kind of medium for the author's penetrating insight and crystalline prose.

"Primo" is a witness account, related without embellishment on a stage with cold gray walls. It's rich in fascinating detail, the sort that generates a chill even if you've seen countless other Holocaust dramas. Levi in one interlude explains that the numbers tattooed on inmates' arms had geographical, even social significance: Low numbers were possessed by the dwindling survivors of the Polish ghettos; those in the range of 116000 to 117000 were Greek Jews from Salonika, and so on. (Levi mentions his own number, 174517, again and again.) The meaning ascribed to the numbers is another bit of evidence of how the camp's inmates clung to any shred of identity, a struggle that Sher honors in this succinct, finely crafted monodrama.

Those with any depth of knowledge of the Holocaust or Levi's work will not find anything of factual revelation here; "Primo" treads a well-worn path through Nazi cruelty. Nor is the focus on Levi's psyche. The play does not, for example, attempt to unravel the circumstances of Levi's apparent suicide in 1987, when he was reported to have hurled himself down a staircase in his Turin apartment building. But even if the historical framework is familiar, there's something of the irresistible in a classical actor of Sher's stature taking on a literary figure as esteemed as Levi.

Reflecting the analytical sensibility of his subject -- Levi, an Italian Jew, was a young chemist when he was packed off to Auschwitz -- Sher delivers a performance of commendable restraint. He talks to you, in the guise of an older, settled Primo Levi, the survivor Levi, a man who speaks not for your edification but simply because he has to. Dressed in a sweater vest, tie, blue shirt and slacks, the actor conveys a man reflecting on an extraordinary interlude from the comforting ordinariness of everyday life.

Levi, born in Turin to a well-to-do family, was arrested in 1943 after joining an antifascist group. The following year, at 24, he was shipped to Auschwitz, where he managed to stay alive until the Russian Army liberated the death camp early in 1945. Levi's survival is attributable both to kindness -- he was befriended by an Italian worker in the camp who risked his own life, smuggling soup to him -- and to canniness: When the Nazis came looking for slave labor for a rubber factory, his background in chemistry got him a job and a measure of protection from the gas chamber.

That he could pass an oral chemistry exam in German, a language in which he was not fluent, suggests a man determined to find a way to live. "Primo" takes us into the camp in an unusually intimate way, and illuminates the kind of tenacity and good fortune required to make it out in one piece. It also chronicles the birth of a writer. Sher, the adapter of this production, seizes on the book's stark precision. The German academic who administers Levi's oral exam is described as peering at the inmate as if "through the glass of an aquarium." The march of prisoners outside Levi's window, as a band plays, puts the author in mind of a dance of the doomed.

"The music drives them," Levi explains, "like the wind drives dead leaves."

Sher extracts many such haunting images from Levi's prose. Some spectators may find the actor's austere approach a bit dry, but his minimal affect seems entirely apt. Survivors of cataclysms often recall their experiences matter-of-factly, in voices that betray little emotion. Only once or twice does "Primo" seek to convey the indelible scars Levi bore for the rest of his life. The result is an evening that walks an audience delicately along a dark corridor of despair.

Primo, adapted by Antony Sher from "If This Is a Man" by Primo Levi. Directed by Richard Wilson. Set and costume, Hildegard Bechtler; lighting, Paul Pyant; sound, Rich Walsh; composer, Jonathan Goldstein. Approximately 90 minutes. Through Aug. 14 at the Music Box Theatre, 239 W. 45th St., New York. Call 212 239-6200 or visit www.telecharge.com.

Antony Sher's performance in "Primo" is commendably restrained, allowing the haunting images drawn by Primo Levi's prose to flow through him and out to the audience.