Terry Pratchett 
Making Money [EPUB ebook] 
A Novel of Discworld

Amazingly, former arch-swindler-turned-Postmaster General Moist von Lipwig has somehow managed to get the woefully inefficient Ankh-Morpork Post Office running like . . . well, not like a government office at all. Now the supreme despot Lord Vetinari is asking Moist if he’d like to make some real money. Vetinari wants Moist to resuscitate the venerable Royal Mintso that perhaps it will no longer cost considerably more than a penny to make a penny.Moist doesn’t want the job. However, a request from Ankh-Morpork’s current ruling tyrant isn’t a "request" per se, more like a "once-in-a-lifetime-offer-you-can-certainly-refuse-if-you-feel-you’ve-lived-quite-long-enough." So Moist will just have to learn to deal with elderly Royal Bank chairman Topsy (ne Turvy) Lavish and her two loaded crossbows, a face-lapping Mint manager, and a chief clerk who’s probably a vampire. But he’ll soon be making lethal enemies as well as money, especially if he can’t figure out where all the gold has gone.