War against the Lord Ruler was the toughest thing for the rebels initially and later they realized that taking care of the empire was almost impossible. The Lord Ruler was controlling everything in the empire for thousands of years and everyone considered him to be a god. Because of this fact, no one ever tried to rebel against the supreme ruler.
However now at the start of this second part, all of us know that the ruler has been killed but the problem is that Kelsier i.e the one who defeated the emperor is also dead. Both of the enemies were unable to save themselves in the battlefield. Brandon Sanderson starts talking about Vin in this novel which shows the intentions of the author very clearly. The author has made Vin, the main character of this second part.
Vin has to fight against the enemies and at the same time she has to face the political games in the kingdom which are new for her. There are several enemies who want to overthrow the rule from the inside. The old battle axe i.e Michael Kramer has done it again by narrating this one by Sanderson. Kramer knew what the story needed because he happens to be expert in dealing with these kind of stories.