Iris and the Implausible Passage

Wessex, Britannia, 642 A.D.
Iris, Princess of Wessex, has run away from an unwanted marriage.
Britannia will never be the same.

With the fall of the Roman Empire centuries earlier, Britannia has been left to the hands of warring kings, and none is more feared or hated than Penda, the ruthless tyrant of Mercia. Determined to squash all opposition, Penda has threatened to destroy the small kingdom of Wessex unless the king hands over his eldest daughter Iris in marriage to Penda's nephew.
When Iris discovers these secret plans and threats, she runs away, and thus is sent on a whirlwind adventure across Britannia, accompanied by, among others, her worry-wart sister, a farm boy named Charr, and a mysterious messenger who isn't what he seems to be. Their goal? To appeal to the one force capable of stopping Penda's cruel regime, King Oswald of Northumbria. If they fail, Iris loses her freedom, her future, and the lives of those she holds dear.