Florence, 1518. Da Vinci's astonishing machines work, and the Industrial Revolution has happened centuries early. When Pasquale, a young painter, teams up with the hard-drinking journalist Machiavegli to investigate a murder in a locked tower room, they stumble into a conspiracy of politics, necromancy and assassination - and as they pursue the case through Florence's acetylene-lit streets the only certainty is that they could be next on the hit list.