Her father, King Redrought 'Bear of the North', stresses that she not only is adept in the subject of fighting but has the sharp mind of a competent scholar.
The Polypontian Empire, led by General Scipio Bellorum, have lost few battles, never a war, and have taken control of most of the countries around them, save Icemark and some others.
It is in one of these Polypontian territorial wars that Redrought sacrifices his entire army, including himself when the last soldier kills him in a surprise attack.
He does this to give Thirrin time to prepare to fight off the rest of the empire's forces, make an alliance with the Wolf Folk, evacuate Frostmarris (Capital of Icemark) before the entire Polypontian army invades.
After defeating a small Polypontian army, Thirrin succeeds in reaching the Hypolitan people, an Amazon-like tribe, who were forced out of their lands for they could not live the way they wanted to, much like the exodus of the Hebrews.
She embarks on a quest to find new allies for the Icemark, resulting in alliances with the Vampires and the mythical and ferocious Snow Leopards.
But he has no intention of acting like a good little prince and sets off to find some of the greatest allies the Icemark could hope for.
Meanwhile, back in Frostmarris, Thirrin and her allies are at war with the Polypontian Empire, led by Scipio Bellorum and his two sons.
This time the empire has a new weapon at their disposal - giant airships that can drop bombs hundreds of feet from the air to the ground.
She inevitably chooses the dark and begins trying to murder her little brother, Charlemagne, for "stealing" her parents' love.
She later causes the death of her brother, Cerdic and many soldiers of The Icemark by manipulating the leaders of the allies' minds and making them go into a battle that they can't be successful in.
Then, she attempts to murder Charlemagne as he "returns to the north with a blade of fire in his hand" (as stated in Oskan's prophecy).
This has caused the Polypontians to break up and many civil wars have started to take their place with the defeat of the Polypontians at the end of the second book, The role of antagonist then settles on Erinor of Artemision and her Tri-horns (Triceratops used as command platforms/siege weapons, similar to war elephants), and Oskan's father Cronus, his Ice Demons and his granddaughter, Medea.
Responding to a plea for help from the Empire, a reluctant Thirrin leads her army into the heart of what was once enemy territory.
However, by invading the Empire to confront Erinor, the Icemark is left open to an invasion from the Darkness (Cronus and his ice demons).
Oskan, entrusted with the secret knowledge that Dark Adepts cannot kill the ones they love without dying, defeats Cronus and Medea at the cost of his own life.
[2] When his brother, the King, is killed in battle, Prince Redrought must rally his people and learn to defend his tiny kingdom against savage supernatural invaders – werewolves, vampires and zombies.
Redrought must take the fight to enemy territory in The-Land-of-the-Ghosts, and it’s there he will fall or stand forever in the legends of the Icemark.
The eastern invaders had similar fighting methods to the Polypontians, in particular, their tendency to overwhelm their opponents by sheer force of numbers.
At the beginning of the story, The Icemark had enemies to the north (The Land-of-the-Ghosts) and to the south (Polypontus) as well as to the east and west (Sea Raiders: Zephyrs and Corsairs).
According to Maggiore's history lesson, the navy of the southern continent helped in the defeat of the Corsairs and Zephyrs in the great Battle of the Middle Sea.
Though enemies of The Icemark, the vampire King and Queen and their undead peoples might join them against the Polypontian Empire for their mutual benefit and safety.