Over time, these bewildered residents realized that someone was lurking in the woods. When Knight was apprehended, he estimated he’d committed 40 robberies per year. His was the largest burglary case in the state. “Maybe the world,” Finkel adds.

Image Michael Finkel Credit... Christopher Anderson/Magnum Photos

Be prepared for occasional flourishes like that one. (Another: “Christopher Knight, you could argue, is the most solitary known person in all of history.”) A few sentences in this book are sprayed with that inexplicable men’s-magazine hyperbole cologne.

Much of “The Stranger in the Woods” is devoted to logistics: How Knight bathed (sponge baths), how he kept warm (pacing), how he eluded detection. (He cooked with a camp stove rather than a fire, for example. Because where there’s smoke. ...)

Finkel, to whom Knight gave stunning access while in jail — especially for a hermit — also does a fine job conveying the idiosyncrasies of his subject’s character. He was awkward and blunt, yet almost formal in his diction. He brimmed with persnickety literary opinions. He avoided looking at people’s faces — “there’s too much information there” — which may have contributed to the state’s three possible diagnoses for him: Asperger’s syndrome, depression or schizoid personality disorder.

Finkel makes a convincing case that none of these labels are especially apt. Isn’t it possible he just wanted to be alone?

Though my question persists: How alone was he?

“The Stranger in the Woods” is involving and well-told; it certainly casts its spell. But there are inconsistencies in Knight’s story.

When he was first caught, for instance, Knight had trouble calculating his age, because he seemed not to know what day or year it was. But he stole plenty of watches and radios while he was in the woods — he was intrigued by Rush Limbaugh — which suggests that he must have had some idea. And while we’re on the subject of electronics: This is a man who once stole a small television, which he powered with a stolen car battery. If he was so close to civilization, how could no one hear it when he tuned in to Ken Burns’s “The Civil War”? I could go on.