This is the latest (I believe) Discworld novel, following pretty closely on Going Postal. It's definitely Discworld. The world continues to follow its own internal logic, making entirely too much sense for something so silly at its core, and the story itself careens through bizarre and amusing situations deftly, with occasional laugh-out-loud funny bits. But it doesn't have the spark of really skewering any societal institutions or saying a great deal about the human condition, which means it's not quite as wonderful as I've been expecting from the last few. A good read, but not great; recommended for die hard Pratchett fans, but anyone who isn't yet a die hard fan probably should seek out Thud or Going Postal instead. 7 out of 10.
**** PLOT SUMMARY -- MASSIVE SPOILERS ****
Moist von Lipwig is bored. He's successfully turned the Post Office around; it's running so wonderfully now that he isn't really needed. So the book starts out with him nearly getting killed scaling the wall of the Post Office and breaking into his own office. Lord Vetinari comes along and offers a new job: take over the Royal Bank and the Mint. Despite his dissatisfaction with his current job, he balks, but Vetinari forces him to take a tour, where he meets the current management, a feisty old lady named Mrs. Topsy Lavish and her yappy dog Mr. Fusspot, who both take a real shine to him. Such a shine that when Mrs. Lavish dies the next day, she's already rewritten her will. She's left her 50% stake in the bank to the dog. And since her late husband lad left 1% of the bank to the dog, the dog is the chairman. And further, she's left a very large stipend for Mr. Lipwig, on condition that he move into Topsy's apartment at the bank and take responsibility for the dog. And also a personal letter to Mr. Lipwig, explaining that she's placed an even larger sum in escrow with the Assassins' Guild to off him if he should be so unwise as to refuse her offer.
So Lipwig steps in to try to run the bank and the mint. The mint is a small bunch of geriatric craftsmen who handcraft coins, mostly in their own houses rather than on premises. They're not making enough money, and Vetinari wants to fire up the economy to inspire his big plans for the city. The bank itself is actually run by Mr. Bent, a savant who can tell with a single glance whether there is an error in a page of figures, but who is utterly devoid of all humor, and who is quite obsessed with how necessary it is that the money be backed by gold. Lipwig is inspired to introduce paper money, but he needs someone who can design money that's intricate enough it can't be counterfeit, so he conspires to steal the greatest forger in history out of jail just before his execution (for forging stamps that were better than the real ones). Meanwhile, Lipwig's fiancee Adora Belle (the golem activist) is off on a secret mission trying to rescue some golems buried under hundreds of feet of sand in a Dwarvish possession, and Cosmo Lavish is quietly going round the bend, obsessed with trying to become Lord Vetinari. His assistant Heretofore is contriving to make enough money feeding the obsession to make a comfortable life for himself somewhere else; this leads to Cosmo's coming into possession of Lord Vetinari's stygium signet ring (or perhaps a nearly perfect copy of it). Stygium is a magical metal which glows brightly in the fainest light and blazes with fire if exposed to sunlight. Cosmo's finger is rather thicker than Vetinari's, but he manages to cram the ring on, and goes forward trying to discredit Lipwig and return the bank to Lavish control. Mr. Bent claims that a clerk has made an error in a set of figures, but upon multiple checks, no error can be found. Mr. Bent has made a mistake. He goes nuts and disappears. Lipwig can't find him anywhere, and he's needed to keep the bank running for the introduction of the new bank notes. He finally realizes that he must have hidden himself in the vault with the gold. Since he took the key in with him and left it in the keyhole, they can't get in, so he has Gladys (a golem who has unwisely read a book of advice for proper young ladies and has decided to be a lady) break into the vault. Unfortunately, this attracts the attention of the Watch (who are also guards at the bank), and while they find Mr. Bent, they also discover that the gold is missing from the vault.
Adora Belle returns to the city, and with some help from Unseen University, they start to realize that the golems -- who are coming underwater from their resting place -- are likely to be a problem. It seems that Umian is a terribly ambiguous language, and what they thought was four golden golems may in fact be four thousand golems. Lipwig has a mad idea that the golems can be the value backing the paper money. Vetinari convenes a court of inquiry, which is disrupted by a clown who throws pies at the assembled Lavishes (Lipwig throws himself on one meant for Vetinari), and then reveals himself to be Mr. Bent. Pucci Lavish, desperate to get some attention for herself, reveals how the Lavishes stole the gold years ago. The golem army arrives, and nobody can figure out how to command them until they start answering Lipwig's commands. Vetinari isn't actually terribly happy that Lipwig has just put himself in command of an army that could easily take over the world. (It seems that the key is to be able to command them in Umian while wearing gold clothes. The silly gold Postmaster General suit has done the trick.) Lipwig gets most of the golems to bury themselves, reserving the horses (who are incredibly fast) for postal purposes and claiming a few hundred to power clacks towers. Everything seems to have settled down, though Vetinari seems to be concerned that Lipwig is too popular and seems to be planning to put him in charge of the tax system next (since that will obviously make him a less popular figure.)