IF ANYBODY COULD HAVE been prepared for what happened to Joan Didion, it should have been Joan Didion. At 70, she is the author of five novels and seven works of nonfiction, all of which are distinguished by enormous intellectual force, an impatience with sentimentality and a general intolerance for bunk. Didion is one of the great clear thinkers and dry-eyed observers of her generation. When people talk about somebody being a tough customer, Didion is the kind of person they're talking about.
Then, on the night of Dec. 30, 2003, Didion's husband John Gregory Dunne, also a writer, suddenly slumped...