If you die, you may come back to life as a Reboot. You're stronger, faster, colder, more ruthless, more resilient -- and the longer you were dead, the better a Reboot you are. 
 Unsurprisingly, they're used as soldiers. And in the dystopian future Texas of "Reboot," it takes a good-boy Reboot to remind the Rebootiest of Reboots that there is something to be said for the human heart. Weave in some solid, bloody action scenes and a secret conspiracy that may be taking down the lesser Reboots, and you have a solid sci-fi thriller. 
 Like all Reboots in the Republic of Texas, Wren works under HARC (Human Advancement and Repopulation Corporation) for law enforcement. She's a One-seventy-eight, which is how long she was dead before she rebooted -- she's cold, efficient and virtually unstoppable. So when she meets Callum Twenty-two, she's both annoyed and baffled -- he's still very human in his thoughts and attitudes. 
 And as she tries to whip him into shape, Wren discovers that something strange is happening at HARC. Experiments are being performed on some of the lower-number Reboots, turning them into mindless savages -- and after her superiors demand that Callum be eliminated, Wren must do the unthinkable in order to keep him alive. 
 "Reboot" is grittier and bloodier than your average dystopian/sci-fi teen novel -- splatters of blood, broken bones, guns and the occasional berserker rage from chemicals. But it's not a graphic bloodbath. It's just a very grim story, and Amy Tintera does an excellent job telling a very slow-building story, even if the first half sometimes feels a little slow. 
 Most of that first half is all about Callum slowly breaking through Wren's icy, unfeeling shell -- while he doesn't transform her into a whole new person, he does touch her with his steadfast morals and kindness. Even though he's weak, his goodness can impress someone who valued strength above all else. There IS a romantic element to their connection, but Tintera wisely doesn't make it too intrusive or instant. 
 But things rev up in the second half, which switches the focus more to the dastardly deeds of HARC (which is only slightly more dastardly than real-life corporations) Tintera shows a knack not only for the more personal, subtle interactions (such as the tragic scene where Callum tries to reconnect to his old life) but also for some blood-spattered action scenes and conspiracies. 
 Those seeking a slightly darker, bloodier dystopian tale might like "Reboot" -- despite a slow first half, it's a solid, powerfully-written sci-fi tale.