A Thread of Grace By Mary Doria Russell Ballantine 464pp., $14.95 Author Mary Doria Russell tossed a coin to determine which of her characters would live and which would die. It was an attempt, she says, to recreate life's blind luck when war turns the world turned upside. Russell's third book, a historical novel entitled A Thread of Grace, marks a change for a writer best known for science fiction in which God, morality and midrash all find a place. The same themes carry on in this story, set in northern Italy after that country's occupation by Germany. Raised a Catholic, Russell was a happy atheist until the arrival of her son initiated a religious quest. Catholicism and Judaism appealed, but Jesus as more than mortal was too great a barrier, so Reform Judaism it was. "One of the things that made it possible for me to come back to religion was the Jewish sense that it doesn't matter what you believe; it's how you behave." Embracing Judaism also meant taking on the Holocaust, with all its theological implications. So it's no coincidence that tragedy is a constant companion in Russell's most recent book. Over a dozen major characters make up the cast, including a rabbi and a priest, a Jewish war hero and his mother, the rabbi's family, a beautiful teenage refugee turned partisan and a trio of SS officers, one of whom is a doctor. For reasons of his own, Renzo Leoni, a hero of a war with Abyssinia, helps the doctor desert. Each bears a tremendous feeling of guilt; Leoni for his role in killing 42 civilians in a hospital, and the doctor for his role in the mass murder of defectives and undesirables. How they struggle through this calculus of death is one of the major themes of the book, as is love, and Italy itself - a country in which, says Russell, half the population spent its time hiding the other half. "There was a wonderful Italian joy in circumventing the laws they didn't care for - it was an indoor sport." A sport that kept 85 percent of Italy's Jews alive until the war's end. At book readings, Russell explains, the audience seems to identify with the Italians and their everyday goodness. But then she speaks to them of present-day horrors, or tells them to imagine living in a different America the day after September 11; an America in which police surround your neighborhood and a family comes to you for help, frightened and desperate. "Statistically," says Russell, "you would have watched. Don't kid yourself. The risks wouldn't have been worth it; that's what tens of millions of people in World War II decided. Recognize how difficult that was, and now challenge yourself." Russell understands the human drive for self-preservation. Religion, however, demands action, encouraging us to rise above our natural instincts. "If not you, who? If not now, when? Get off your ass," Russell cheekily paraphrases the Talmud. Living in a world where civilization is only a word often means pushing through a wall of ignorance, selfishness and arrogance. "It's very Jewish isn't it? You do what you can to repair the world when you see an opportunity." Russell, a paleo-anthropologist who dropped out of academia to write, has won several awards, including the John W. Campbell Award and the Arthur C. Clarke Prize. A newly discovered asteroid named for the world she created in her first two books, Rakhat, proved the most substantial honor. The Sparrow, Russell's first book, is now being made into a movie. She'll continue the historical trend in her next book, turning to the 1921 Cairo peace conference and the birth of the modern Middle East. An amateur theologian in her first two books, Russell says Thread of Grace made her an amateur historian. She is an amateur in the best sense of the word - one who works for the love of it. In all three books, Russell demands that we never forget the good, never submit to cynicism and never give up, no matter which way the coin falls.