Kal-el Albus is the deposed crown prince of an empire toppled by the Wind Revolution, living under a false name and carrying a quiet vow of revenge against Nina Viento, the revolution's figurehead. He and his sister Ariel enroll in the aerial division of Cadoques High aboard Isla, a flying island setting out to find the End of the Sky. There he falls at first sight for a classmate, Claire Cruz, and trains as a fighter pilot until an attack in mid-flight drops him back into the war.