Hidden City of Alchemy is a tale of alchemic science, unique automatons, a smart heroine with an odd nose (a hereditary defect from her father's side), and a secret society. Set in London and Paris in 1925, smart and somewhat defiant Elizabeth Peters discovers a dangerous family secret in a hidden diary after her mother is kidnapped by German spies. She is sent on a whirlwind adventure from London to Paris while learning the shocking truth about her ancestor and about a chemical that could destroy humankind if it should fall into the wrong hands.