Making Money is the continued adventures of Moist von Lipwig, the con-artist who was bullied into going straight and re-establishing the Ankh-Morpork post office in Going Postal. The post office is now running like clockwork, and Moist is growing bored, doing stupid, dangerous things with lockpicks and climbing-gear just to convince himself that he's still bent.
But all that changes when he is put in charge of Ankh-Morpork's major bank, in charge of the city's thoroughly disordered monetary supply. Like The Truth, which recapitulates much of the true history of the early days of newspaper publishing as a comic fantasy novel, Making Money tells the tale of the difficult transition from the gold standard to an economy based on fiat currency. And, like The Truth, Making Money manages to extract an enormous amount of humor, pathos, and keen insight from the subject, especially through its use of well-drawn and well-realized characters (the secret to good comedy).
There are 33 Discworld novels out there, and I imagine that being confronted with that many books would be a little daunting (on the other hand, Vernor Vinge told me that when he finally started reading Pratchett, a couple summers back, it was like being 10 and discovering a writer like Baum or Howard with a huge corpus of works, something that hadn't happened since he'd caught up with all those writers, decades before). Luckily, the books largely stand alone. You can probably enjoy Making Money without reading any other Discworld novel, and you can definitely enjoy Making Money if you read Going Postal first.
Moist von Lipwig is fast becoming my favorite Discworld character, a flawed, likable, canny comic hero who manages to surprise and delight with each volume. And Pratchett remains one of my favorite writers in the world, a man who is clearly having so much fun, he must be breaking some law, somewhere.