Young princess Finé, the daughter of the Archduke of a small alpine country, travels to the neutral land of Westria to seek help against the Germanian empire that is invading her kingdom. But her plans go awry when she's captured by the Germanians, and transported by air back to their capital of Neu-Berlin. Then a strange light appears at the back of the plane, and a witch begins to awaken...

Finé and Izetta escape the burning wreckage of the plane on the back of a rifle. But squad of Germanian pilots participating in the invasion of Eylstadt hear the transport's distress call and move to intercept them. Izetta is forced to use her magic to fight them off, breaking the rule her grandmother gave her. When the enemy planes are shot down and driven away, Izetta takes Finé to join the retreating Eylstadt army, where she reminisces about how they met.

With Izetta's victory over the Germanian army fresh in people's minds, the army of the Dukedom decides to make her into a national icon and announce her to the world. She's given the finest white dress they have to offer and a huge ceremony is arranged with journalists from all over the globe. But before she can be used in combat, they need to unravel the secret of her strength, which means she must travel to a hidden location with a girl who doesn't like her very much at all.

Izetta is powerful enough to fight whole armies, but her strength is limited. She can only use her abilities near certain ley lines, and outside them, she's no different than a normal girl. When the Germanian army attacks in a spot far from these ley lines, the duchy is forced into a corner: how can they repel these foes without giving up the secret of Izetta's strength?

Izetta's victory has won a brief peace for the dukedom, and the princess intends to enjoy it. Together, they practice dancing, and go to a pie shop. But there's trouble brewing in the background, as young private Jonas has discovered her secret. How far is Seig willing to go to keep the country safe, especially when innocents are involved?

Izetta and the princess have come to the nation of Britannia to ask for help from the allied forces. In order to win their favor, Izetta is sent to destroy a Germanian aircraft carrier that's floating in the North Sea.

Rickert lands in the dukedom of Eylstad on a secret mission: to uncover the secrets of the witch. He's sent to infiltrate the old castle of Eylstad, which is being heavily guarded by the Royal Guard. But his mission takes an unexpected turn when he runs into Bianca, the head of the Royal Guard...

All is quiet in the dukedom as the Germanian army redirects its forces to deal with a coastal invasion by the allied forces. But the silence is suddenly broken by a deadly feint attack, and Izetta is sent to save the day. But when she arrives, she's met with another Witch! Who is this new witch, and can Izetta defeat her?

Izetta has been defeated by Sophie, the true White Witch. Sophie is out for revenge against the Dukedom for the crimes their ancestors committed, and she'll gladly work with Germania if they'll help her destroy it. Izetta and the princess barely escape to a hidden fortress in the mountains, but Izetta is so badly injured she can't walk. How can she stop Sophie from destroying her country?

The capital of Landsbruck has fallen, and Izetta and the princess are chased into the mountains. As the imperial forces track them down, Seig makes Izetta an offer: he's willing to give her the other half of Sophie's magic stone. With this powerfulitem she fight toe-to-toe with Germania's witch, but it causes the user tremendous pain, and shortens their lifespan...

Germania has loaded a massive bomb with magical energy that threatens to destroy the entire Dukedom. It will launch soon, and the only way to stop it is to defeat Sophie. Using the magic stone, Izetta flies to Germania for one final battle.