The Shadow Master — Craig Cormick

In a land riven with plague, inside the infamous Walled City, two families vie for control: the Medicis with their genius inventor Leonardo; the Lorraines with Galileo, the most brilliant alchemist of his generation.

And when two star-crossed lovers, one from either house, threaten the status quo, a third, shadowy power--one that forever seems a step ahead of all of the familial warring--plots and schemes, and bides its time, ready for the moment to attack...

Assassination; ancient, impossible machines; torture and infamy--just another typical day in paradise.