Cinder ends on a definite cliffhanger. The ending sequence begins with Cinder arriving at the ball. She is a complete mess by the time she arrives in order to warn Kai about Levana's nefarious plotting. Cinder does manage to get a dance in with Kai, and she uses that as an opportunity to warn Kai. Levana shows up and reveals to Kai that Cinder is a Lunar. Kai isn't sure what to believe, but Cinder confirms her origins, and that leads them to discuss the politics of this situation.
The discussion takes a turn for the worse when Levana uses her Lunar powers against Cinder; however, Cinder's own abilities emerge at that point, and she is able to resist Levana. Cinder then makes an escape attempt, but she loses her too-small cyborg foot on the stairs. As a consequence, she is captured. The book ends with Dr. Erland visiting her and teaching Cinder some basics about her powers. He also gives her a new foot and hand complete with some hidden surprises. Lastly, he reveals that Cinder is actually Princess Selene and urges her to escape and join him in Africa. The book ends with Cinder preparing for her escape.