In this third book set in a post-apocalyptic, post-technological Britain, Fever and her mother go on a perilous mission north from London to find a rumored black pyramid that may hold secrets of much-needed Ancient technology. Characterization is deep and revelatory; themes are rich and seamlessly interwoven; and the plot is complex and packed with propulsive action.

The third (and final?) Fever Crumb story reminds readers of the serious themes beneath Reeve's often madcap, always entertaining tales. Following the events of A Web of Air (2011), a subdued Fever has returned to London. It's not long before she heads north with her mother, following rumors that a mysterious structure that may hold the key to Stalker brains has been breached. Meanwhile, London nears the mobility it will enjoy years into the future (Mortal Engines, 2003, etc.), but the northern nomads are ready to challenge London based on a young girl's prophetic dreams. Whew! Beneath the plot run three narratives: of Fever, discovering the truth about the Scriven and her own humanity; of Cluny Morvish, reluctant prophet and, it turns out, another of Godshawk's experiments; and of Charley Shallow, who once tried to kill Fever and is now an upstanding young sociopath who pulls a lot of strings. There are few truly happy moments here, and lots of violence, but the rich worldbuilding continues to hold surprises, and the writing never falters. Most hopeful--although perhaps unexpected--is a possible romance for Fever; the not-fully-resolved ending leaves hope that the feelings might be reciprocated. The implication that only away from London and science can Fever find happiness echoes the themes and tensions between technology and nature Reeve has explored throughout this and the Hungry Cities quartet. Quiet and somber, but still deeply satisfying. (Steampunk. 13 & up)

Gr 8-11 Picking up where A Web of Air (Scholastic, 2011) left off, this final installment in the trilogy won't disappoint Reeve's many fans. Fever Crumb returns to London, but the place where she grew up is now unrecognizable. It has been transformed into a city on wheels, thanks in part to Wavey, Fever's mother and London's Chief Engineer. The nomad tribes of the North are threatened by this new moving city and plan to attack. Meanwhile, Wavey hears of a black pyramid in the North Country that might contain useful information about the past. The mother and daughter are inevitably drawn toward the structure, but, on their journey, tragedy strikes, leaving Fever to make some tough decisions and choose alliances she never thought possible. She also meets Cluny Morvish, a member of one of the nomadic warrior tribes and travels with her. Fever's friendship with Cluny changes her perspective on many things, including raising questions about her own sexual identity, which Reeve handles delicately. Beautifully complex language and a fully realized, highly creative future world will draw in readers, although those unfamiliar with the previous books will struggle with characters and concepts. Fever's journey concludes with satisfying answers to long-standing questions about the basis for her society and her own heritage. For die-hard fans of science fiction, it doesn't get much better. Mandy Laferriere, Staley Middle School, Frisco, TX