In nineteenth-century England, a boy is about to discover a mysterious mechanical world he may never escape. Ten-year-old Jack Foster has stepped through a doorway and into quite a different London. Londinium is a smoky, dark, and dangerous place, home to mischievous metal fairies and fearsome clockwork dragons that breathe scalding steam. The people wear goggles to protect their eyes, brass grill insets in their nostrils to filter air, or mechanical...