Maybe it's because his first novel, The Mezzanine, is so minutely burned into readers' minds that some critics have been thrown off by Nicholson Baker's recent reinvention as a political agitator. I am one of the legion of fans — call us the shoelace-staring crowd — who haven't stepped onto an escalator or spied a CVS bag since The Mezzanine appeared in 1988 without thinking of his microscopically rendered commuter's paradise, and so it was fitting that Baker and I arranged to meet and discuss his new book, Human Smoke (Simon & Schuster) — an alternative history of the buildup to the Second World War — in Boston's South Station.

Baker, nursing a cold and wearing the kind of sweater that makes New England famous, had driven from his house in southern Maine to meet my train; with apologies that his brain was "all in a muddle" (it was not), he settled into a booth at the station's pub to talk about pacifism, firebombing, Churchill's war strategy, and the provocations that may have led to the attack on Pearl Harbor in 1941. Oh, and newspaper preservation, the pleasures of underhand Frisbee throwing, and the derailleur that Baker coveted for his 10-speed bike while growing up in Rochester, New York. As readers of his incredibly varied work know, Baker possesses a rare, almost innocent enthusiasm for the things that pass unnoticed, often in plain sight. "When I was writing The Mezzanine, I just wanted to write a book about a guy who works in an office building and rides the escalator to work every day; I thought that was the right proportion," Baker, now 51, said over a messy hamburger. "But in extraordinary times, when you've been attacked and your country is at war — I became more political."

Human Smoke is the story of the "good war" told in vivid historical vignettes, many of them culled from the newspapers of the day. It begins in 1892, with Alfred Nobel's prediction that his explosives will put an end to human warfare, and it ends on December 31, 1941, on the eve of what Baker calls "the real horrors" of the war: the Final Solution, the firebombing of cities, and the atom bomb. Many of the characters (FDR, Churchill, Hitler, Gandhi) are mythical in stature, but they are humanized as never before. Others have walk-on parts and provide a chorus of reason in a world that has lost its bearings: In one memorable episode, Albert Speer's father tells his son, "You've all gone completely crazy."

Baker, an avowed newspaper buff — his lauded American Newspaper Repository project saved endangered original print runs of the New York World, New York Herald Tribune, and other daily papers from the incinerator — tried to re-create the daily flow of news with Human Smoke. "I wanted to have that feeling that history is something you assemble in your own mind," he told me. "Just like a newsreader or a radio listener did at the time." And in writing about a world where print still reigned supreme, Baker found an unexpected affinity with his larger-than-life subjects: "All of these leaders, especially Roosevelt and Churchill, began every morning by reading the papers. They were compulsive newspaper readers. So they were buffeted by the same opinions on one side or the other that everybody else was from day to day. They're human beings. They could be monumentally self-deceived one day and incredibly canny the next." Baker — who is "somewhat" Quaker, married to Margaret Brentano (with whom he cowrote The World on Sunday), and the father of two — marched against the war in Iraq and treats his activism, and his work, with a disarming modesty. He dismisses the historiography he employs in Human Smoke as "primitive," but it is really something else: a passionate investigation of the human cost of war by a novelist with a conscience.