Set for release in Canada and the U.S., the as-yet-untitled work will explore the "intriguing, little-known story of the origins of professional hockey," as well as early Stanley Cup battles and "the ascent of Toronto teams and players that have long been forgotten," according to the publisher.
The subject "goes right to the heart of Canada's national identity," according to Simon & Schuster president Jonathan Karp.
Canadians didn't always cheer on hockey heroes, Harper said in a statement.
"The early days of professional hockey featured outsized personalities who fought pitched battles to shape the game we know and love today," he noted.
"Writing this book has taught me a lot about hockey and a great deal more about Canada. I hope all who read the book enjoy it as much as I enjoyed the experience of writing it."
Harper is getting some editorial assistance from noted author and journalist Roy MacGregor. He had originally hoped to publish the book in late 2006.
All author royalties from the book's sale will go to the Canadian Forces Personnel and Family Support Services department — specifically to the Military Families Fund, which offers emergency financial assistance to military families.