Illea is a fictional nation in the popular book series "The Selection" by Kiera Cass. It is a monarchy that emerged after the collapse of the United States, featuring a rigid caste system that divides its citizens into different social classes. The royal family, led by the king and queen, resides in the capital city, where they oversee the country's governance. The story primarily follows America Singer, a young woman from the lower caste who enters a competition to win the heart of Prince Maxon. The competition, known as the Selection, involves young women from various castes vying for the prince's affection, highlighting themes of love, class struggle, and personal growth.