Miss Clara Marie Stanton's family may be eccentric, but they certainly aren't insane. London, England, 1860: When Clara's ex-fiancé begins to spread rumors that her family suffers from hereditary insanity, it's all she can do to protect them from his desperate schemes, society's prejudice, and a lifetime in an asylum. Then Clara's grandfather Drosselmeyer brings on an apprentice with a mechanical leg, and all pretense of normalcy takes wing.

Theodore Kingsley, a shame-chased vagabond haunted by the war, wants a fresh start far from Kingsley Court and the disappointed father who declared him dead. Upon returning to England, Theodore meets clockmaker Drosselmeyer, who hires him as an apprentice, much to Clara's dismay.

When Drosselmeyer spontaneously disappears in his secret flying owl machine, he leaves behind a note for Clara, beseeching her to make her dreams of adventure a reality by joining him on a merry scavenger hunt across Europe.

Together, Clara and Theodore set off to follow Drosselmeyer's trail of clues, but they will have to stay one step ahead of a villain who wants the flying machine for himself—at any cost.