Second Book in the Red Queen series (possible book 1 spoilers below):
Pursued by Maven, now a vindictive king, Mare sets out to find and recruit other Red-and-Silver fighters to join in the struggle against her oppressors. But Mare finds herself on a deadly path, at risk of becoming exactly the kind of monster she is trying to defeat. Will she shatter under the weight of the lives that are the cost of rebellion? Or have treachery and betrayal hardened her forever?