An English knight of chivalry, Bowen, mentors a Saxons prince named Einon, in his ideals with the hope that he will be a better king than his tyrannical father King Freyne. While suppressing a peasant rebellion, the king is killed and Kara, a young peasant girl, accidentally causes Einon to be mortally wounded. Einon's Celts mother, Queen Aislinn, has him taken before a dragon and asks it to save the boy's life. The dragon replaces Einon's wounded heart with half of its own on the promise that Einon will rule with justice and virtue. However, Einon proves even more tyrannical than his father by enslaving the former rebels and forcing them to rebuild a Roman Empire castle. Bowen, believing the dragon's heart twisted Einon, swears vengeance on all dragons.
In the 9th century in the north of Great Britain, a druid circle foresees a "falling star" from the constellation Draco_(constellation), with Brude - one of the druids - summoning a Picts clan known as the "Painted tribe" to slaughter the druids and lead the clans to war against the southern kingdoms over Hadrian's Wall. A druid apprentice called Lorne escapes the slaughter of the druids.
When the king of Roman Britain dies, the dragon who shares his heart must find a new ruler, but the monarch's Fraternal twin grandchildren go to war over the throne.
Lukas, a young farmer whose family is killed by savage raiders in the countryside, sets out on an epic quest for revenge, forming an unlikely trio with a majestic dragon and a swashbuckling, sword-fighting mercenary, Darius.
