On a July afternoon in 1984, Dan and Ron Lafferty, members of a tiny Mormon fundamentalist sect, appeared at the door of their sister-in-law's American Fork, Utah, duplex, forced their way in, beat her, and slit her throat with a 10-inch boning knife. Moments earlier, Dan, a chiropractor and father of five, had found his 15-month-old niece standing in her crib. ''I'm not sure what this is all about,'' he told her, ''but apparently it's God's will that you leave this world; perhaps we can talk about it later.'' Then he cut her throat.
The Lafferty murders are the centerpiece of Under the Banner of Heaven, Jon Krakauer's fascinating exploration of fundamentalist Mormonism, a harsh, decentralized faith that encourages men to take multiple wives and is practiced by more than 30,000 people in scattered pockets throughout the western U.S., Mexico, and Canada. Most fundamentalists don't kill women and babies any more than most Muslims fly planes into office towers. But, Krakauer argues, the Lafferty murders, as well as the widely publicized 2002 abduction and rape of Elizabeth Smart, are firmly rooted in radical Mormon history and theology. ''Heaven'' is a departure from Krakauer's ''Into Thin Air'' and ''Into the Wild,'' those macho page-turners about misadventures in the wilderness. But it is every bit as engrossing.
Krakauer emphasizes that the mainstream Mormon Church -- a vigorous, conservative religion practiced by 11 million people worldwide -- doesn't recognize fundamentalists, whose doctrines make the strictures of the mother church (no booze, no coffee, don't even think about being gay) look downright permissive. The fundamentalist wing began to emerge after 1890 when the Mormon Church backed away from polygamy -- a tenet of the religion dating back to 1843, when Joseph Smith, Mormonism's charismatic and libidinous founder, codified a supposed revelation from God concerning plural marriage. A handful of zealots, convinced that polygamy was a divine mandate, migrated to remote desert enclaves where they have practiced their stern faith (some hallmarks include white supremacy and the subjugation of women) virtually unimpeded ever since.
Raised as mainstream Mormons, the Lafferty brothers became increasingly drawn to fundamentalism. (Dan spanked his wife when she disobeyed, and he took a second wife.) In the early 1980s, the Laffertys began to follow Prophet Onias, an accountant-turned-holy man who believed God spoke directly to individuals. Brenda Lafferty, a former beauty queen who was married to Dan and Ron's brother, Allen, found fundamentalist precepts loathsome and said so. And one day Ron Lafferty claims he heard God tell him to kill her; her baby, a ''child of perdition,'' also had to go.
''Heaven'' features a lengthy analysis of the Lafferty trials, in which Krakauer draws the distinction (a mighty fine one) between religious fanaticism and insanity. But while the murders are the most lurid stuff in the book, they are ultimately less chilling than Krakauer's description of the role of women in the fundamentalist world -- as evidenced by the Elizabeth Smart case.
Authorities believe that in 2002, a fundamentalist named Brian David Mitchell kidnapped 14-year-old Elizabeth from her well-to-do Salt Lake City home. His wife, waiting at a campsite, told Smart to undress, then Mitchell allegedly raped his new ''bride.'' (Krakauer writes that Mitchell maintained after his arrest that his actions were not criminal because they were a ''call from God.'') For the next nine months Smart lived as his wife and, curiously, did not attempt to escape. Krakauer suggests that Smart, a devout Mormon girl, was primed by her upbringing to obey a male authority figure spouting scriptures, however bizarre.
The Smart case stirred up a media frenzy. When Mitchell was arrested and Smart returned to her parents, President Bush telephoned. But, Krakauer points out, what happened to Elizabeth happens every day to anonymous daughters of the desert. In arid, isolated hamlets, adult men regularly force pubescent girls into harems, marry their stepdaughters, and sire scores of children who are then supported by taxpayers. (Since only a man's first wife is recognized under U.S. law, additional ''wives'' are legally single and their offspring qualify for government support.) The men are rarely prosecuted.
The only problem with this marvelous book is that Krakauer tries to do too much. In addition to the Lafferty case, he tosses in long, vivid segments on Mormonism's strange, violent history, the hair-raising biographies of polygamous wives, accounts of mainstream Mormon pageants, and updates on succession battles within fundamentalist sects. It's all riveting, if sometimes hard to track. Then again, does it really need to? ''Under the Banner of Heaven'' is rambling, unsettling, and impossible to put down.