Scrivener's Moon - Book 3 - Fever Crumb Prequel to Mortal Engines Quartet

In a future land once known as Britain, nomad tribes are preparing to fight a terrifying enemy - the first-ever mobile city. Before London can launch itself, young engineer Fever Crumb must journey to the wastelands of the North. She seeks the ancient birthplace of the Scriven mutants "The Scriven People are brilliant, mad - and dead. All except one, whose insane creation is nearly complete - a giant city on wheels."--Cover