I saw this book in my recommendations on my Kindle for about a year. I judged a book by it's cover, and I didn't like it before I even read it! THIS WAS AN AWESOME BOOK! 
 It's a retelling of Cinderella. Cinder is a cyborg and mechanic. Kai is the prince. You can probably guess how it ends if you read Cinderella, but it ends differently here. Queen Levana, queen of the Lunars (aliens/moon people) plans on marrying Prince Kai and killing him, making herself empress and able to take over the world. It's up to Cinder to stop her, but she can't do it alone. The next books are about other fairy tales (little red riding hood, rapunzel, snow white) and all four girls are going to come across each other some how and band together to defeat the evil queen, save the planet, and find their HAPPILY EVER AFTERS :D! 
 Age recommendation: 12+