Moist Von Lipwig is back, and still working hard to keep his neck free from Vetinari's noose. This time he is made responsible for the public safety (and the city's financial stake) regarding a radically new form of transportation: steam powered locomotives. Along the way he has to manage the growing ingenuousness of goblins, help stave off a Dwarfish civil war, and keep an increasing amount of, well, change from getting out of hand. And at it's heart it is "change" that is the subject of this novel, and how people deal with change. Some embrace it, some fear it, and some see it as a way to profit. It's not a "laugh out loud" Discworld book, which will be a disappointment for some, but I quite enjoyed it.