Genghis, the great khan, is dead, slain by the hand of one of his trusted inner circle. The great armies and princes have gathered in the city of Karakorum to give their oath to Ogedai, Genghis' son. His enemy, his brother Chagatai, attempts a coup before the oath-giving but fails, and the following day Ogedai is sworn in. The nation has a new khan at last to follow Genghis.
But known only to himself, Ogedai's heart is weak. Karakorum is his tomb and he hardly expected to live long enough to become khan. He cannot kill Chagatai, as there must be one strong enough to rule when Ogedai's heart gives out. Instead, he gives him a khanate of the west, gifting the ancestral homelands to his younger brother Tolui. Ogedai then sets out on his one and only campaign: to finish Genghis' task of annihilating the Chin empire.
Meanwhile, the great leader Tsubodai sweeps into the west: through Russia, over the Carpathian mountains and into Hungary. He splits his forces into three, so that no reinforcements can come from north or south as he drives on west. Poland is sacked in the north, Serbia in the south. At the moment of Tsubodai's greatest triumph, as his furthest scouts reach the northern mountains of Italy, news from Ogedai reaches them. Against Tsubodai's wishes, the khan's son and heir, who rides with him, decides to return home with the army, where a khan must be chosen once more.