The year is A.D. 781. King Charles of the Franks is crossing the Alps with his family and court on a journey to meet with Pope Hadrian. One frosty night he speaks to his young son Carl: When we come to Rome you will know that I am naming you my heir. One day you will rule over all my lands. . . . But the King already had an heir, Pepin the Hunchback, mockingly called Gobbo. Was he to be dispossessed? Yet Carl sees that Charlemagne is determined to...