Killbox picks up right after Doubleblind, Jax's diplomatic mission to Ithiss-Tor having succeeded. The first thing she does? Quit. She's had enough of diplomacy. It doesn't take long for her and the rest of the crew to find other employment, though, as the Conglomerate wants to hire March as Commander of a potential Armada. Conglomerate power is weak after decades of control by Farwan Corporation and the crime syndicate headed up by Jax's mom -- aptly named The Syndicate -- along with countless other renegade smugglers and criminals -- are basically crippling anyone with expectations of safe space travel or living in colonies outside the main systems. The Conglomerate needs a peace-keeping, law-enforcement Armada, and they want March to build them one out of the exact same criminals and smugglers currently causing so much devastation.
The first half of the book is mostly logistics, gathering crew (which mostly involves March persuading old mercenary buddies to join them, and then press-ganging the rest), brainstorming, and putting together the framework for the Armada. The second half follows Jax on the Triumph as they put the Armada into action, saving colonies and ships from smugglers and raiders and slavers, and of course, the Morgut, the alien race who end up being the main source of conflict in the story. The Morgut are making more and more encroachments on peaceful territory, and it's the Armada's responsibility as the only peacekeeping force in their part of the galaxy to try and stop them. It soon becomes clear, however, that the Morgut attacks so far have been merely a precursor to a large-scale invasion. The Morgut, for unknown reasons, have decided to abandon their homeworld and colonize/eat the parts of the galaxy mostly occupied by humanoids. Jax is right on the front of this as one of the only humans who can understand Morgut language (thanks to the brain chip she got back in Doubleblind). She also happens to be the only person who has figured out how jump through grimspace without using beacons -- she can jump from one place to another without any lag time, and it almost killed her the first time she tried it. Her life is a never-ending ball of fun.
For the most part, this book was pretty good. I just had a few issues with it that somewhat marred my enjoyment (it probably didn't help that the last book was so much fun for me, there was almost no way this one wasn't going to be at least slightly disappointing). My biggest complaint was the relationship between Jax and March, which previous to this had already been threatening to become an annoying back and forth thing. I thought they'd taken care of their shit in the last book, but apparently not, as March makes the boneheaded decision to break up with Jax for the entire duration of their time in the Armada, supposedly because he can't give her special treatment and because he needs to emotionally separate himself from her for the sake of the job. This is stupid because: a) EVERYBODY ALREADY KNEW THEY WERE DATING BEFORE THE ARMADA EVEN STARTED AND NOBODY CARED, and 2) It's very clear from what happens after that March didn't save himself or Jax any heartache either, in fact their separation probably made them more miserable. The worst part of this is that not only does March make this decision for idiotic reasons, but the OTHER CHARACTERS ACTUALLY AGREE WITH HIM. It bugged me.
Jax herself continues to have great character growth, but her continued insistence that the nanites/chips in her head make her scary to other people are ineffective, because seriously, hello? Who wouldn't want to have those special powers? They aren't scared of you, Jax, they're jealous. And secondly, because Aguirre gives us no proof that other people dislike Jax's headware, just Jax telling us they do.
The final thing that bugged me in this one is that Ramona up and sacrifices herself out of nowhere at the most crucial moment of the Morgut battle, and it plays out as extremely convenient. It would have played better if Aguirre had spent more time with Ramona and Jax's relationship, but there was too much other stuff in the book for her to do that. Total deus ex machina. Other than that stuff, still enjoying this series, looking forward to the last two books.
And, hey, when are we going to learn March's first name? It is bothering me so much that we don't know. And neither does Jax! What! He's put his penis inside of you, woman, and you supposedly love him more than anyone else in the galaxy. Learn his damn name.