On a distant island village, there is a legend that anyone born with horns will bring about calamity. Such a boy was born named Ico. To ensure the safety of their village, Ico is offered as a sacrifice at a nearby castle. However, he escapes and finds a young girl named Yorda imprisoned there as well. While trying to escort her out, they are attacked by the angered spirits of the castle and Yorda's mother, the queen of the castle. Together, Ico and Yorda must work to flee from the castle before they can be claimed by the spirits.