Kill by Numbers

Former assassin Raena Zacari thinks she's left the past behind. The Imperial torturer who trained her is dead, the human empire is disbanded, and she is finally free. But Raena is troubled by a series of nightmares that always seem to end with her shooting an ex-lover in the head. She needs to get her mind clear because there's a flaw in the most commonly used starship drive-and the band of media-obsessed pirates she's fallen in with is right at the heart of the controversy.
With humanity scattered across the galaxy, she's going to have to rely on the alien crew members of the Veracity to help her put the pieces together. It doesn't help that the Templars- wiped out in a genetic plague while Raena was imprisoned-have left booby-trapped biotechnology scattered across the galaxy.