Set 150 years after the first book, Shinn’s Samaria now features da Vinci-esque engineers trying to figure out the secrets of flight (for non-winged non-angels) and transportation. Archangel Alleluia, raised abruptly to the position after her predecessor Delilah suffers an injury, finds herself learning more than she cares to know about the actual mechanics behind the entity they know as Jovah. Soft-spoken Alleluia and her easygoing engineer friend are a pleasure to read; their circumstances are tense but they treat one another with kindness and mutual respect, which is utterly refreshing. A very satisfying conclusion as well, though Shinn leaves the door open for further development.