London"s geniuses are being picked off by a vicious killer, and Emma Bannon, a sorceress in the service of the Empire, must protect the next target, Archibald Clare. Unfortunately he"s more interested in solving the mystery of the murders than staying alive... In a world where illogical magic has turned the Industrial Revolution on its head, Bannon and Clare will face dark sorcery, cannon fire, high treason and the vexing problem of reliably finding hansom cabs in the city.