Terry Pratchett 
Making Money 
(Discworld Novel 36)

»Whoever said you can»t fool an honest man wasn»t one.»
The Royal Bank of Ankh-Morpork is facing a crisis and needs a shake-up in management. Cue Moist von Lipwig, Postmaster General and former con artist. If anyone can rescue the city»s ailing financial institution, it»s him. He doesn»t really want the job, but the thing is, he doesn»t have a choice.
Moist has many problems to solve as part of his new role: the chief cashier is almost certainly a vampire, the chairman needs his daily walkies, there»s something strange happening in the cellar, and the Royal Mint is running at a loss.
Moist begins making some ambitious changes . . . and some dangerous enemies. Because money is power and certain stakeholders will do anything to keep a firm grip on both . . .
»As bright and shiny as a newly minted coin; clever, engaging and laugh-out-loud funny» The Times
Making Money is the second book in the Moist von Lipwig series, but you can read the Discworld novels in any order.