Newt's emerald

Garth Nix

After Lady Truthful's magical Newington Emerald is stolen from her she devises a simple plan: go to London to recover the missing jewel. She quickly learns, however, that a woman cannot wander the city streets alone without damaging her reputation, and she disguises herself as a mustache-wearing man. During Truthful's dangerous journey she discovers a crook, an unsuspecting ally, and an evil sorceress but will she find the Emerald?