The Skinwalkers are another form of Night Human, so this book takes place in the Night Human/Day Human world, but it is about a completely different set characters. However, we did meet Cassie in the last Day Human book, she is the witch that came to help Devin. I really love this world that the author has created. Cassie has been kept in the dark about the Night Humans her whole life and when she finally learns about everything her world just kind of gets turned upside down and she is suddenly thrown into all this craziness that she doesn't want. I am excited to see where this goes. Looking forward to the rest of the series.