as the only character in "Underworld" who rates first-person narration, Nick is the novel's center, but there are over a dozen other people crowding this book, all them connected to him in some way. The most appealing are Klara Sax, an older sculptor with whom Nick had a brief affair; her ex-husband, Albert Bronzini, who coached Nick's brother through a boyhood phase of chess wizardry; and Marvin Lundy, a widower who collects baseball memorabilia and has some interesting theories about Greenland and the shape of Mikhail Gorbachev's birthmark. J. Edgar Hoover -- celibate and ever vigilant against germs and other forms of infiltration -- makes a few appearances, paralleled by an equally disinfectant-crazed nun doing charity work in Nick's now-devastated old neighborhood in the Bronx. So does Lenny Bruce, shrieking, "We're all gonna die" throughout the Cuban Missile Crisis. There's a highway sniper and several people who briefly own the baseball that Bobby Thomson hit into the left-field stands on Oct. 3, 1951, a homer that won the pennant for the New York Giants, an event that one character describes as "the last time people spontaneously went out of their houses for something. Some wonder, some amazement." DeLillo cherishes the moment because it happened just before mass media gained the power, by endless reproduction and repetition, to drain such experiences of their immediacy. He has that wildly sentimental romanticism about baseball common in intellectuals, but beyond that, "Underworld" isn't really nostalgic. It's the story of America's (and Nick's) awakening from the dream of the Cold War, which like most dreams seemed so convincing and compelling in the moment, only to strike us as utterly pointless later. "Does anyone remember why we were doing this?" Nick asks a Russian giving him a tour of a heartbreaking radiation clinic on the outskirts of Semiplatinsk in Kazakhstan. "For contest," the Russian replies. "You won, we lost. You have to tell me how it feels. Big winner." Picking up a theme that runs through "Libra," DeLillo suggests that the contest was little more than an excuse to lay plots and keep secrets, that the Cold War supported covert activities, not the other way around. Secrets are DeLillo's great passion, and the reason why his (male) characters love the Mafia, nuclear weapons research, intelligence work, conspiracy theories, dossiers and even baseball trivia so much. They fantasize about locating the Underworld where secrets are hidden and they study varieties of what Nick calls "Dietrologia ... the science of what is behind something." Nick thinks of "God as a force that withholds himself from us because that is the root of his power ... This is what I respected about God. He keeps his secret." A few pages later, fresh from an adulterous tryst during which he confesses his own Big Secret (he shot a man in his youth and has never told his wife), he muses, "You withhold the deepest things from those who are closest and then talk to a stranger in a numbered room. What's the point of asking why?" Indeed -- if you paused even momentarily to ask, you might collide with your own unappetizing propensity to play God. It's a fine theme, a wise and true one, but it rules over "Underworld" in a way that no idea, however burning, ought to rule over any novel; it comes first. The book has many smaller delights -- its sweating, feverish images of New York City, elderly characters who inhabit the density of their long lives in a way that old people in fiction seldom do, and always DeLillo's gimlet eye, which notes how among the children gathered around a summertime ice cream vendor there's always "the kid with ink on his tongue," and how "when people tell rat stories, the rat is always tremendous" -- but even these are like vibrant organisms kept isolated under glass. Even at its best, there's a museum-quality hush to DeLillo's prose in this book. Perhaps the source of the problem is Nick himself. "Underworld" includes long, tiresome accounts of his "Mean Streets" youth -- shooting pool, picking fights, slinging the beefy slang of his native Bronx -- none of which succeeds in making him interesting. "I've always been a country of one," he explains solemnly. "There's a certain distance in my makeup, a measured separation." He calls it "lontananza" after an Italian word for masculine remoteness. He pretends to curse it, but really it wraps him in the same glamorous mystery that cloaks his brother Matty's top secret weapons research. Matty speculates that "when Nick dies a team of metaphysicians will examine the black box, the personal flight recorder that's designed to tell them how his mind worked and why he did what he did and what he thought about it all, but there's no guarantee they'll find the slightest clue." Or they might just find that there's nothing particularly significant in there. Nick's secret, the one that supposedly provides the book's suspense, proves anticlimactic. It's only the hiding, after all, that makes it intriguing, that makes Nick's wife curious, and makes Nick himself feel like a dark, brooding, complicated, serious guy, a lone drifter, a hit man, a spy. Like the precious enigmas of the Cold War, "all the banned words, the secrets kept in white-washed vaults, the half-forgotten plots," Nick's sequestered soul turns out to be something outdated, pretentious and ultimately banal. And even that's a brilliant idea: centering a teeming novel like this, an era, around a vacuum, a man whose heart is as sterile as J. Edgar Hoover's specially designed toilet ... but it's still an idea. When I think of the novels that strike me as great, the ones that seize me up and carry me along like a river, I think of characters -- Jane Eyre, Hester Prynne, Huckleberry Finn, Raskolnikov. People who kidnapped their authors and set them on uncharted paths, people who, when they enter a scene, make me think, "Ah, it's you." "Underworld" bleeds as a result of never settling on such a character, for brushing past a few more promising candidates and centering on boring old Nick (who shares more than a few biographical details with his creator). I found myself pining for the rambunctious, bewildered, commodity-bedeviled Gladney family from my favorite of DeLillo's books, 1985's "White Noise." It was just a little, comic novel -- 326 pages to the 827 of "Underworld" -- about some ordinary people who worried about sugarless gum, television, crying babies and death. It didn't try so hard, and it felt more alive than all these pages of glorious prose about epochal home runs and the Zapruder footage and the bomb. I can't help but admire "Underworld" for its scope, for the task DeLillo dared to set for himself and the monumental perfection of the results, but I can't love it. There's a secret to engineering that sort of greatness that even J. Edgar Hoover couldn't capture for his files.