Scarlet is, you guessed it: The second book in the Lunar Chronicles.
I loved this book so much. The book switches view points every couple chapters.
One part tells the story of Scarlet, the granddaughter of a french farmer. She is delivering her produce when she meets a Wolf.
Little does she know this shy street fighter knows something about Scarlet's missing Grandma They embark on an epic quest to find her and rescue her from the weird gang that thinks she is hiding something or other.
The other half of the story follows Cinder as she escapes from prison, bringing along the very annoying Thorne, an ex-american pilot and thief.
There are also little chunks of Kai doing stuff too. Mainly mooning around about Cinder and the fact that he hast to marry the evil moon queen to keep the earth from being invaded.