The literary critic Frederick Karl was recently quoted as saying that Joan Didion "diminishes whatever she touches." It's a remark that becomes more interesting when you twist it into a compliment: Joan Didion writes from a vantage point so remote that all she describes seems tiny and trim and uncannily precise, like a scene viewed through the wrong end of a telescope. That cleared space where she stands, that chilly vacuum that could either be intellectual irony or profound depression, gives her a slant of vision that is arresting and unique.

Democracy, her fourth novel, is narrated by an "I" who is apparently Joan Didion herself, untransformed….

And what is her story? Well, Jack Lovett, a world traveler whose business dealings don't bear close investigation, meets Inez Christian in Hawaii on her seventeenth birthday. They have a brief affair and then part. Inez marries Harry Victor, who eventually...