Anyone who has ever set out to report a true story has discovered that it rarely ends up being what they first imagined. Like a strong current, once you enter you are no longer in complete control.

This was true of one of the first and most famous of the so-called “nonfiction novels,” Truman Capote’s remarkable (if journalistically tainted) In Cold Blood. He set out to find one story when he went to Kansas, and ended up with something else entirely, something that would ultimately reveal as much about him as it does about the killers at the center of his book—perhaps more.