The first thing you’ll want to do with a copy of “The Lampshade,” Mark Jacobson’s new book, is to remove its dust jacket, fold it neatly, and shove it as far down into your trash can as it will go. You’ll feel better almost instantly.

Mr. Jacobson’s book is about a lampshade fashioned from human skin, a lampshade that may or may not be a Nazi relic, made from a concentration camp victim or victims. Its unfortunate dust jacket — diaphanous, crinkly to the touch — mimics the feel of that skin. It’s a direful thing to have in your hands, a desiccated version of Lady Gaga’s skirt-steak dress. Bad taste, bad vibes — get it gone.

What you’re now holding is this: an antic, improbable and resonant nonfiction book, one that’s part historical horror story and part squalid crime caper. If you changed its locations to South Florida, it could pass for a darker and slightly better-than-average Carl Hiaasen novel.

“The Lampshade” reveals what happens when a lamp — probably stolen, its shade said to be made from human skin — turns up at a post-Katrina rummage sale in New Orleans. The asking price: $35. The seller, we discover only later, is among the most loathed men in New Orleans, a drug-addled cemetery bandit.

A friend of Mr. Jacobson’s buys the lamp out of perverted curiosity. He gives it to the author, a contributing editor for New York magazine, asking him if he’d like to look into its origins. The buyer also clearly wants the macabre object out of his house. What happens next is … well, plenty happens next. DNA tests determine the lampshade is no hoax: it is indeed made from tanned human skin. But that’s all the tests reveal. The skin is too brittle to give up further information. As a forensics expert explains, “Some things are more dead than others.”

Mr. Jacobson travels to the Buchenwald concentration camp in Germany, where human lampshades were supposedly made to order for Ilse Koch, the so-called Bitch of Buchenwald, who was married to the camp’s commandant. Mr. Jacobson also speaks to a former head of collections at the United States Holocaust Memorial Museum. Few answers are forthcoming.

The consensus among historians is that these Nazi lampshades may well be a myth, as are the bars of soap Nazis allegedly rendered from Jewish corpses. But soldiers, journalists and survivors reported seeing such lampshades at Buchenwald after its liberation, even if no one can locate one today. Mr. Jacobson isn’t tempted to abandon his search.

As “The Lampshade” moves along, it gets shaggier. Mr. Jacobson talks to cantors, to World War II veterans, to Holocaust deniers, to Nazi memorabilia collectors and to an actress who played the evil Ms. Koch in a sadistic porn film. There are more fluky cameos here than in a Quentin Tarantino movie.

He fields midnight phone calls from the New Orleans musician Dr. John, and consults Cyril Neville, a member of the Neville Brothers band. He drops in on David Duke, the white supremacist, now living in Austria and as blithely deranged as ever. Mr. Jacobson describes Mr. Duke’s dyed blond hair as resembling “a half-fallen soufflé,” and notes that his teeth are “whiter than buffed Chiclets.”

Sometimes “The Lampshade” is too shaggy. Mr. Jacobson’s visit with a Dominican spiritualist is a less-than-essential moment, and what are we to do with the news that the author has named the lampshade Ziggy? Mr. Jacobson’s laid-back writing can resemble stoner prose, as if he’s fighting an urge to add the word “dude” to his sentences. The lampshade, he writes, “had become the creaking flying saucer of the Holocaust.”

Mr. Jacobson’s book passes a primal test, however. When you put it down, you look forward to picking it up again. This is largely because it becomes an entangling meditation on not merely Nazi atrocities but on the nature of authenticity. It considers, too, other far-flung topics: the history of skinning and scalping humans; the roots of Holocaust denial; New Orleans prisons during Katrina; black funeral traditions versus white ones; Mr. Jacobson’s own Jewish upbringing in Flushing, Queens.

Mr. Jacobson charts how the lurid, almost pornographic idea of Nazi lampshades has percolated through popular culture. He quotes Leon Uris novels and Woody Guthrie songs, as well as Sylvia Plath’s poem “Lady Lazarus,” with its lines about Plath’s soon-to-die body, with its face as fine as “Jew linen” and her skin “bright as a Nazi lampshade.”

Mr. Jacobson spends a lot of time in New Orleans, and his book is yet another bluesy, scuffed-up paean to that city’s wonders. He quotes the Orleans Parish coroner, Frank Minyard — Mr. Minyard is also a central character in “Nine Lives,” Dan Baum’s New Orleans book — describing how Katrina has “shaken things loose,” in ways good and ill.

All the same, Mr. Jacobson doesn’t let New Orleanians or other Southerners off the moral hook. He reminds us that Mr. Duke got 55 percent of the white vote when he ran for Louisiana’s governorship in 1991. He brings his story full circle when he observes how some white Southerners once slaked their own thirst for human taxidermy.

Mr. Jacobson describes the 1899 lynching of a black man, Sam Hose, in Georgia. Then he writes: “Many viewers had approached the ravaged corpse to cut off pieces of his skin to take home as souvenirs. Later Hose’s heart, knuckles, and facial skin were displayed in local store windows and offered for sale.”

Beauty may be skin deep, Redd Foxx reminded us in a vastly different context, but ugly goes clear to the bone.