1066, William of Normandy is about to embark to conquer England. Stopped on shore by adverse winds, some clashes begin in his ranks. The duke is deep in prayers. He is wearing around his neck a scandinavian idol and a christian cross he received in his infancy.
Thirty years earlier, Robert the Magnificent, William's father, is about to leave for a pilgrimage in Palestine. He presents William to the Exchequer of Normandy as his heir. Despite the opposition of Renouf, a norman baron, and the bastardy that besmirch the reputation of young William, the Norman parliament accepts.
One year later, the news reaches Normandy: Robert is dead. It's chaos. Osbern, seneschal of the dukedom, hides young William. To escape from the menacing Norman barons, Osbern and William follow an underground river guarded by Hel the sibyl, who talks to him about his viking origins. They safely reach Osbern territory.
We are in 1040, William has grown up. Osbern trains him to sword fight in the middle of a river, on a large flat rock. Guilbert and his nephew Gui de Brionne, heir of Burgundy, come to warn them that they are no longer able to contain the barons : they intend to threaten them again. Oblivious of the immediate danger, Osbern does not know that the mercenaries are not far away. They kill Guilbert de Brionne on his way back and kidnap his nephew Gui de Brionne. Suprised by the unexpected attack, Osbern and young William's bodyguards are outflanked. With the help of Willem, Osbern's son, William escapes his attackers, while Osbern is fatally wounded and dies.
Seven years later, Willem, en route on the paths of Normandy, warns William that a squadron of the Exchequer is coming and is willing to get it over with him. Among the soldiers of the squadron is Gui de Brionne, favourite of the Exchequer for William's title. Gui and William fight a duel and William manages to escape.After this new setback, the barons decide to use a strong-arm tactics and gather an army. William flees and reaches France to ask for the help of the king of Francs. The king agrees to help him if William gives up the pagan practices and build christian buildings so that Rome does not take umbrage at the alliance with « the bastard ». On the eve of the battle, William gets prepared. He puts the tiny viking idol around his neck and hides it under his tunic. Both armies confront one another at the Val des Dunes battle. William's bravery impresses his soldiers: he stands on the front line and is a main actor of the victory. He will spare Gui de Brionne and the norman barons' life.
We are back in 1066. In a gesture for inner peace, William burries in the sand his father's tiny pagan idol and christian cross. The winds have changed, it is time to leave for England...