In modern-day San Francisco, fourteen-year-old Riley, Taisia, Skyler and Evelina discover they have supernatural powers. Riley can produce fire, Taisia can bend nature to her will, Skyler controls water and Evelína commands thunder and lightning.
They are the legendary Astoríans, the Guardians of Planet Earth – except they don’t know that yet. In fact, their true identities are kept a secret by Meridius, the Guardian of Celestial Light.
After the young Astoríans embark on a quest to discover what makes them unique, Meridius senses a sinister power growing in the universe and begins to fear for their safety. But then, mysterious acceptance letters to Aditus High School whisk the girls out of their ordinary homes and into an adventure that will change their lives forever.