The Clocktaur War Duology - The Wonder Engine

In this brilliant sequel to The Clockwork Boys, old foes resurface, and Slate and Caliban are forced to deal with the echoes of their past choices. Slate and her crew have arrived in Anuket City, the city of artificial marvels where Clockwork Boys are created. But the secret of their existence is as mysterious as ever. Slate has a history in Anuket City, history which just won't leave her alone. And her increasing attraction to Caliban is driving her up the wall. Caliban is, of course, too noble to do anything about it. As Slate's history in the city grows more entangled with their mission, the group's chances of survival seem to be getting ever slimmer. If they're to stand a chance of destroying the Clockwork Boys, Slate must confront her past, and find a way to stop it from killing them all.