You wouldn't expect Native American Shamanism & Celtic Mythology to blend well into a cohesive storyline. Yet book after book, C.E. Murphy succeeds in delivering a story that keeps you on your toes. I love the fact that you never quite know what to expect.
Joanne Walker, born Siobhan Grainne MacNamarra Walkingstick, began as a disbeliever in book 1 and has gradually learned to use her shamanic powers throughout the series. You definitely need to have read the first 6 books in the series before starting this and I would go one step further and strongly recommend the short story in Winter Moon. Events that began in "Banshee Cries" take on new importance and culminate in Raven Calls.
In this book we learn a lot more about Jo's Celtic heritage and specifically about her mother, the Irish Mage. Time travel, time loops and jumps through spirit world levels could confuse those not familiar with Jo's history, but I personally loved all the twists and turns.
I will definitely be picking up the next two (and final) books in this series.