Justice Ascending by Rebecca Zanetti

Before surviving the Scorpius bacterium, Tace Justice was a good ole Texas cowboy who served his country and loved his mama. After Scorpius, the world became dark, dangerous, and deadly… and so did he. The Vanguard medic is stronger, faster, and smarter than before, but he’s lost the line between right and wrong. His passion is absolute, and when he focuses it on one woman, there’s no turning back for either of them.

Sami Steel has been fighting to survive right alongside Tace, convincing the Vanguard soldiers she’s one of them. In truth, Sami is a former hacker turned government agent who worked at The Bunker, where scientists stored both contaminants and cures. Only she knows the location, and she’s not telling. Yet when sexual fire explodes between her and Tace, she’ll face even that hell again to save him.