Before his death in October 2002, Stephen Ambrose faced embarrassing charges that he had plagiarized material in his much-acclaimed works of history. It was a sad footnote to a career that saw the publication of more than 20 historical books, many best sellers.

But as it turns out, Ambrose wasn't quite finished. In September, Simon & Schuster will release his final book, submitted to the publisher just months before he died.

And this time, there will be no controversy over missing quotation marks and attribution: This book is a novel.

This Vast Land: A Young Man's Journal of the Lewis and Clark Expedition, is the fictionalized diary of 18-year-old George Shannon, a boy who actually accompanied Lewis and Clark on their expedition. Ambrose's story is geared for teens and adults, who will no doubt benefit from the man's knowledge. After all, Ambrose wrote the hugely popular Undaunted Courage: Meriwether Lewis, Thomas Jefferson, and the Opening of the American West.

"My father's passion for the story of Lewis and Clark compelled him to move beyond the bounds of nonfiction," says Hugh Ambrose, the author's son, in a press release.

He has also moved beyond the bounds of those troublesome quotation marks. As if channeling Cormac McCarthy, even when his character is reporting dialogue in This Vast Land, there's not a quote mark in sight. Ambrose, it seems, has had the last laugh.