Clockwork Revolution

In a future where power and industry on an Empire are still driven by coal, sweat and steam, the aristocracy live very different lives from the men and women who keep the engines of the city working. That is, until the evening an Artist, a Princess and a Thief meet on a rain slicked tenement roof. They won't realise it until much later, but that meeting will change their lives and the fate of the everyone in the city.
As the entire culture of the city starts to crack under the pressures of social unrest, a bloody and painful revolution appear inevitable but is this small group of freaks and outsiders the heroes of the revolution or are they the cause of all the problems?