Harbinger Series (Wheeler) is a young adult series about a magical sky world supported by Mysteries magic and an opposite working world below. The series follows Sera, a princess from above, and Cettie, an orphan from below, as they carve their own paths and learn about their place in their magical world. This Harbinger Series by Jeff Wheeler is not to be confused with the Harbinger Series by popular young adult author Jennifer Arnemtrout.