The French groove is a hinge that allows a book to open easily. It's a staple feature of nearly every modern hardcover book. The skilled fine hand-binding the Keoughs sought would create a book that opens smoothly without the benefit of a French groove.
After dozens of binderies worldwide begged off on their idea, essentially calling it harebrained, the Keoughs hit pay dirt. The folks at Felton Bookbinding, a small, old school Canadian bindery run by an Englishman, a Scotsman, and a Swede, were willing to take on the challenge.