I always wondered why Mark Twain didn't number the last chapter in "The Adventures of Huckleberry Finn." Instead, he titled it "Chapter the Last." Was it so we'd be discouraged from ever thinking of Huck as anything more than that mischievous kid we'd come to know and love?

Regardless of Twain's reasons, any author picking up where Twain left off is an audacious literary move, one Norman Lock has made with his most recent — and 15th — book of fiction, "The Boy in His Winter." Though in truth, to call it a work of fiction is to tell only part of the story. This book is as much a treatise on memory and time and the nature of storytelling and our collective national conscience as it is a novel in the sense "Huckleberry Finn" is.

Divided into three parts, "The Boy in His Winter" deals first with the 170 years between the end of "Huckleberry Finn" and Hurricane Katrina. Huck and Jim float down the mighty Mississippi without aging, immune from the ravages of the Civil War, startled by the invention of electric lights, told of the horrors of World War I.

The years click by with alarming quickness, and as they do, the reader is left wondering not only about the author's broader conceit that we make of time what it is, not the other way around, but also about what the point of imaging a journey such as this might be.

Indeed, Lock himself is often troubled by just this notion. "Have you considered what this story might mean, or are you taking dictation with no other thought than the payment you'll receive when I have in my hands the transcript of this — what would you call it? An American Picaresque? A chimera spawned by an old man's grotesque imagination? Will anyone care?" Huck asks, and I admit I wondered myself just what sort of book I was reading while turning these pages.

Huck is set free of time on that fateful August day in August 2005 when Hurricane Katrina ravages the Mississippi Delta, literally throwing Huck from his raft and into life. He takes up with a group of roughneck drug smugglers, heads up the East Coast and ends up a yacht salesman in the second and third parts of the book, finally finding his true love in the Netherlands, of all places.

There is no shortage of rhetoric on the nature of time and our memories in these sections, much of it wildly funny and extremely intelligent, and most often Lock's prose matches his purpose to wicked effect. But if you come to this book expecting a yarn like you got in high school when you were assigned "The Adventures of Huckleberry Finn," you will end up finding something else in "The Boy in His Winter."

Peter Geye is the author of "The Lighthouse Road" and "Safe From the Sea." He lives in Minneapolis.