1000 years have passed since earth has become uninhabitable engulfed by a black cloud, covering it in its entirety. Evidence points to sequential massive volcano eruptions or a nuclear war, the fact remains the last human survivors’ dwell amongst 4 massive floating cities, named Cassandra, Bethany, Trishna, and Electra, together amongst other names they are known as “the sisters”, “the four human mothers”, “daughters of Gaia”.