In an alternate 1914 Europe, fifteen-year-old Austrian Prince Alek, on the run from the Clanker Powers who are attempting to take over the globe using mechanical machinery, forms an uneasy alliance with Deryn who, disguised as a boy to join the British Air Service, is learning to fly genetically-engineered beasts.

Polly's visit to her grandparents in Connecticut becomes an extraordinary experience as she encounters old friends and mysterious strangers and finds herself traveling back in time to play a crucial role in a prehistoric confrontation.

Working to overthrow Queen Levana, a fugitive Cinder and her companions search for Rapunzel-like hacker Cress, who has been trapped on a satellite since childhood and who has received orders from Levana to foil Cinder's efforts.