In the legendary era, after the Golden Knights slayed demons, they left a prophecy that a hundred years later, when the two moons eclipsed at the same time, heroes like them would appear in the world... Time flies, and there are two princes with very different personalities in the Kingdom of Morn. The heir to the throne, Fabius (James Edward Franco), is a hero and a warrior, and is highly trusted by the people; the second prince, Teds (Danny McBride), is good at messing up any task, and is dissatisfied and complaining because people have ignored him for a long time. When Prince Fabius was fighting against the evil wizard "Genius Lizard", he rescued the girl Belladonna (Zooey Deschanel) who had been imprisoned for many years, and planned to marry the latter. The Genius Lizard rushed to the wedding scene and abducted Belladonna to complete the ceremony of giving birth to a dragon. Fabius and the reluctant Teds set out on a second journey to rescue Belladonna. According to legend, obtaining the Unicorn Sword is their only chance to defeat the Gila Monster...