At some point in the world's history, a great natural cataclysm threw massive chunks of earth into the sky, creating the current system of floating islands.

Her father dies at the beginning of the series, and Sephie becomes Minister of Meridian, acquiring at the same time a mysterious Sigil, a mark upon her forehead, which grants her an array of powers.

He attempts to use his powers, and his significant political influence, to seize Meridian from Sephie's control, and to create an economic and industrial empire, demanding tribute from other islands, if not conquering them outright.

After learning more about her powers and her family's past, acquiring equipment and support, and meeting new friends and allies, she sets about perpetrating piracy upon her uncle's trade routes and fights him directly on a number of occasions.

While not fully central to the conflict between Sephie and her uncle Ilahn, there are appearances by members of The First who are the Gods of the CrossGen universe, as well as by Samandahl Rey, the main hero of the title Sigil, and others.