The Women Engines

Some women survive their monsters. Cara Artell was rebuilt to become one.
Broken, bleeding, Cara has one shot at escaping her husband. Her sister Alta is the one who drags her to the recruiting centre on Tilt Station, where women like her trade their old bodies and their old lives for augmented limbs, iron discipline and a place among the Comuna-Guardia. Be the engines of change, the posters promised.

When her sister goes missing, every drill, every step deeper into humanity's losing war is one step closer to finding Alta again. Cara tells herself that's the only reason she's still standing. When the man who commands her new sisterhood proves every bit as dangerous as the one she fled, Cara finds an unlikely tether in Sam, a bounty hunter with nothing left to lose.

But loyalty has a price out in the far reaches, allegiances shatter like bone, and the war for what's left of the human race is coming to collect. When Cara finally gets close enough to touch her sister again, she'll learn that some truths cut deeper than the monsters she left behind.
Some engines run on rage. Hers runs on a promise she'll burn the galaxy down to keep.

Also available as an audiobook