The Castle in the Forest By Norman Mailer Random House 496 pages There was a time when Norman Mailer used to talk about the Big Book. It prowled the interviews he gave in the 1950s like a white whale, blasting into view and then disappearing back into the darkness, where it would lurk until the next publication date. With each decade, and each new book, from The American Dream to Executioner's Song, up until The Gospel According to the Son, it seemed like Mailer might still drag his promised catch to shore. Though Joan Didion concludes Mailer finally got his big fish - four times in fact - the lion remains unconvinced. And approaching his 84th birthday, America's most pugilistic novelist has done something unusual. He's beginning to say he may not get it. "I may have made announcements 50 years ago of the kind of book I was going to write," says Mailer at his home in Provincetown, a fishing village turned weekend retreat at Cape Cod's tip. "But I'm not going to stick to those predictions." What's unusual is Mailer is making this pronouncement on the eve of his latest book, his 36th, The Castle in the Forest, an audacious novel that tells the story of Hitler's first 14 years through the eyes of D.T., an assistant of the devil himself. "I am very confident in this book," Mailer says., as if to reassure he's not passing off a lemon. Mailer has worked on the book long enough to lose track of when he started exactly. During the writing, he has done a mountain of research - evident in the book's bibliography - and traveled to Austria. In recent years his knees have given out, meaning he now walks with the aid of two canes. During the course of the interview he does not stand. "There was one early review that was essentially favorable, but it irritated the hell out of me," says Mailer, revealing his old feistiness. "Let's say it irritated the shit out of me. Because the reviewer said in some long-winded way, of course Mailer is just rewriting Freud." Mailer is referring to the book's strong, one might say pungent, scatological theme. "Why? Because I paid attention to toilet training. Well, as a father of eight children I do know a little bit about toilet training." The evidence of this assertion surrounds him. The end tables in the room are stacked four deep with photographs of Mailer offspring. Several paintings of Mailer line the walls - a large one hangs in the front office depicting himself and his sixth wife, Norris Church Mailer, and a friend in Havana. As Mailer winds up into a story about how the painting came about, his assistant Duane lingers to hear it told. Here is Mailer in his element, passing off tales of concupiscence in Havana, reminiscing on taking classes at the Sorbonne after the war, doing a dance on the grave of his past and future critics. Large windows open onto the bay and the ocean beyond. In this comfortable setting, it seems odd that Mailer should be so compelled to delve back down into "the reek of the urine, the shit, and the blood of Luther," so manifest throughout The Castle in the Forest. THIS IS A fascinating, exceptionally dirty book that also happens to want to turn the clock of America's cosmology back 60 years. Mailer believes that the world is run by a threesome - God, man, and the devil - and that Hitler was the devil's response to Jesus Christ. The most vivid scene of The Castle in the Forest involves Hitler's bawdy, raucous, incestuous conception - with the devil inserting himself into young Adolf's soul at the moment of his parents' climax. As provocative as this sounds, Mailer says he is not being facetious. "We can understand Joseph Stalin in a way," he says. "One of the things about Stalin is that he was one of the very toughest men in Russia. Hitler was not that tough. It was as if odd gifts were given to him at extraordinary moments." Mailer says such gifts can only have come from the devil, who he believes works all the time. In the book, D.T. explains the process as if it were a kind of covert CIA operation, with budgets to spend and miniature private loyalties to be won over. In person, Mailer is a bit more specific. "Maybe every year there are 1,000 people invested by the devil or a million people? Then they either come to fruition or they don't." Hitler, in Mailer's view, was a high point, something he says his mother knew in Brooklyn long before Hitler had marched on Poland. "My mother was very affected by Hitler," he says. "When I was nine years old, she knew already, long before the statesmen did, that Hitler was a disaster and a monster. That he was probably going to kill half the Jews, if not all of them." Mailer has long thought he would write a book about Hitler. But first he had to get to The Gospel According to the Son, which told Christ's story in his own words. The idea for it came to Mailer in a Paris hotel room. Mailer couldn't sleep, so he picked up the Bible. "I thought, 'This is such a funny book. It's got sentences that are worthy of Shakespeare, but most of it was dreadful. Then I thought, 'There are 100 writers in the world who could do a better job.' And I'm one of them." Mailer wrote the book and got slaughtered for it, and today, even he admits "I felt I didn't quite bring it off. I felt like I was making a reach for the material," he says judiciously. With Hitler, though, Mailer says he did not feel this barrier. For starters, spending time with a very bad man was not a problem, as he learned from writing about Lee Harvey Oswald in Oswald's Tale. "You know your characters don't need to be there to make you happy with how wonderful they are and how warm-hearted they are and how human they are," he says. "You can write about a monster, and so far as you enjoy writing, enjoy the work." As a Jewish writer, he says he has also long since been ready to approach Hitler with a cool head. "The first time I visited Germany in the '50s I was very much on edge." Not anymore, however. In fact, Mailer says he worked very hard to make the book feel German - reading and absorbing and then channeling it back onto the page. "There is very little known about Hitler's childhood," he says. "He concealed much of it, to the best of his best ability." So Mailer ad-libbed, speculating about Hitler's parents' incestuous relationship to a degree that outstrips history. He also invents a libidinous beekeeper and, most interestingly, invests a good deal of the book's energy into bringing to life Hitler's father, Alois, who emerges as a grabbing, greedy, sexually ravenous customs official. Mailer also manages to make him an almost sympathetic character. "I felt for him," Mailer says. "He is a man. And say what you will about him, he's got balls." Mailer used to put in marathon writing sessions. He even once retreated to a shack nearer the ocean to work, but the sound of the surf destroyed his rhythms. He has been coming to Provincetown for nearly 50 years - part of Deer Park was written here - but it has only been year round in the last two decades. He has become used to five, six hours at a stretch, sometimes without lunch if he became absorbed. Long ago, Mailer might have felt some apprehension with this project, knowing the kind of reviews it would spark. Now he says he doesn't care. But there is one thing that can inspire his old fury: the Iraq war. Mailer's outrage over it boiled over into several blog posts he wrote for Ariana Huffington's blog, The Huffington Post. "The huge shock I felt when that war started was the willful blindness of people who were intelligent enough to know what they were getting into," he says, his gravelly voice rising a register. "And the idiocy of the people who didn't know what they were getting into - like our God-fearing president." Mailer says there might be a lesson here for Americans, one not far off from the bailiwick of this book. "My feeling now is all countries can potentially become monstrous nations - and I think the last few years here, it's not as if we became a monstrous nation. But for the first time in Americans' lives, the possibility is so." In other words, the devil is not entirely responsible for Hitler or any other politician's rise to power. Conditions made it possible, too, and so vigilance of governments is just as important. "Given the hideous conditions in Germany after the First World War, not only the shame and humiliation of losing that war in an extraordinary thoroughgoing way." Mailer continues to rattle off the social context of Hitler's rise. "Given all that, all the conditions were there for a monster to take over the country." And yet, to say that alone created Hitler, to Mailer, is not enough. "I'm not here to guarantee it. But I'm saying we won't understand this unless we go back to the notion that maybe God and the devil do exist!" The writer is president of the National Book Critics Circle.