This is book 2 in Sanderson's Mistborn Trilogy.
I was quite taken by Sanderson's first novel, Elantris. It was an amazing work of fantasy told in one volume, a rare find these days. I'm not a huge fan of Fantasy in general. The books all tend to be cookie-cutter, spending a few chapters building their world, explaining magic, creatures, the lay of the land, etc. I prefer books that get into character and politics, the latter of which Sanderson does quite nicely. At the end of Mistborn, the evil Lord Ruler had been defeated, the skaa (a slave class) had been freed, and the entire political spectrum of the world had shifted.
Book 2 begins with Elend, the loafing, somewhat brattish son of a nobleman, assuming the throne and attempting to put his political ideals into action. He's determined to forge a democracy where a centuries-long dictatorship once stood. There's an immense amount of political maneuvering to be done, and thankfully Sanderson paints these in broad strokes, not getting bogged down in minutiae while still creating a solid and believable "West Wing" scenario.
Vin, the titular Mistborn from book one, has grown into her powers, and now stands as Elend's royal bodyguard. She's overworked, as noblemen from around the land are all seeking to displace Elend's new government and seize power for themselves. The book continues the overarching storyline (the quest to understand who the Hero of Ages was, and why he'she would be able to save the world, and what went wrong when they did). The city falls under siege by two invading armies, and Elend must work to secure his people's safety while Vin works to solve the greater mysteries: the Mist that envelops the world at night seems to be lingering longer into the day, and at times seems almost sentient. On top of that, another powerful Mistborn stalks her in the night, with plans of his own for the future.
The book suffers a bit from "second part syndrome", setting things up for the third book while tying things up from the last book. The action sequences are tightly paced, and I'm definitely excited to see where this all leads. Unfortunately, late in the book, I discovered pages 528-560 were missing from my copy, and I got this a long time ago through Amazon, so there's a couple of things I'm missing (pretty important stuff for book 3 setup). I'll have to hunt down a copy in Borders and sit and read...