Napoleon, back from the island of Elba, had regained power and reconstituted the Grande Armée, which was on the march towards Belgium, where the battle of Waterloo was to take place. Colonel Neuville was summoned by Marshal Ney. Ney entrusted him with a special mission: to go and meet Colonel Reynauld, a renowned royalist who refused to hand over command of his men to the Empire. It was imperative that his men join the Grande Armée. However, beyond their political differences, Neuville and Reynauld are brothers and a strong antagonism separates them. Their duel will be all the more intense for it.