This is book number 2 in the Mistborn series.
The Lord Ruler the man who claimed to be god incarnate and brutally ruled the world for a thousand years has been vanquished. But Kelsier, the hero who masterminded that triumph, is dead too, and now the awesome task of building a new world has been left to his young protege, Vin, the former street urchin who is now the most powerful Mistborn in the land, and to the idealistic young nobleman she loves.