Scarlet by Marissa Meyer -- 512 pages
(Yes, I'm listening to these again. Don't judge.)
Scarlet knows that her grandmother did not run away. Her grandmother is not crazy, and she most likely was kidnapped. Scarlet is ready to do anything to find and rescue her, and Wolf, a street fighter, might be able to help her.
Meanwhile Cinder escapes from her jail cell with another criminal, Thorne, who stole a spaceship from the American military. So, of course, they escape on this spaceship, but they can't stay in outer-space forever. As soon as they reenter earth's atmosphere, they risk being tracked down.
Emperor Kai is being hard pressed from all sides, but mostly from Lunar Queen Levana, who is furious about Cinder's escape, and threatening war if she isn't found.
Scarlet is the second book of The Lunar Chronicles.