Who are the three main characters in downsiders?

* Cadel Piggott, the protagonist, is a downsider who grew up in the Undercity of Ember and has a knack for fixing things.

* Lina Mayfleet, the deuteragonist, is Cadel's best friend and a brave and adventurous girl who is resourceful.

* Lizzie Bisco is a downsider who is wise, kind, and knowledgeable about machines and how they work.