Shadow Collateral by Christy Barritt

Danger is closer than they think.

After Tori Bristow’s special ops brother dies a sudden, suspicious death, she’s wrenched out of her normal everyday life as a traveling nurse and thrust into danger. Convinced there’s more to Nathan’s demise than what she’s been told, Tori follows the clues her brother left behind straight to former military operative Kai Kaleo.
When Tori first approaches Kai, he wants to dismiss her wild theories. But he can’t ignore the mounting evidence that backs up her claims. As the danger escalates, it becomes clear someone powerful is determined to silence them.
Kai and Tori must learn to trust and rely on each other to stay alive and find answers. But as they navigate the dangerous world of secret government programs and deadly conspiracies, they soon discover the shadowy truth lies just beneath the surface—much closer than they could have ever imagined.