To the consternation of the patrician, Lord Vetinari, a new invention has arrived in Ankh-Morpork - a great clanging monster of a machine that harnesses the power of all of the elements: earth, air, fire and water. This being Ankh-Morpork, it´s soon drawing astonished crowds, some of whom caught the zeitgeist early and arrive armed with notepads and very sensible rainwear.
Moist von Lipwig is not a man who enjoys hard work - as master of the Post Office, the Mint and the Royal Bank his input is, of course, vital . . . but largely dependent on words, which are fortunately not very heavy and don´t always need greasing. However, he does enjoy being alive, which makes a new job offer from Vetinari hard to refuse . . .
Steam is rising over Discworld, driven by Mister Simnel, the man wi´ t´flat cap and sliding rule who has an interesting arrangement with the sine and cosine. Moist will have to grapple with gallons of grease, goblins, a fat controller with a history of throwing employees down the stairs and some very angry dwarfs if he´s going to stop it all going off the rails . . .