Christie Golden 
Star Wars: Fate of the Jedi: Ascension 

In this penultimate novel in the bestselling Fate of the Jedi series, Luke Skywalker, his son Ben, and the Sith girl Vestara are in hot pursuit of the dread power called Abeloth, who has joined forces with the Sith in a bid to take over the galaxy. The leadership of the government is uncertain, torn apart by power struggles and infiltrators, while the Sith have a terrible secret that could shake the Jedi Order to its core…