Renegade by Susan May Warren

The last person Sierra Blackwood expects to see is the man whose memorial service she attended three years ago.
For ten years, she’s raised their son alone, told him his father died a hero, and built a life from the ashes of broken promises. Now Rowan “Hammer” Wallace is back—no explanation, no apology, just those devastating blue eyes and a presence that fills every empty space she’s tried to heal.

He doesn’t know about the boy. And she doesn’t know if she can survive losing him again.
But there’s no time for second chances when a killer has you in their crosshairs.

Someone wants Sierra’s ranch—and they’re willing to burn down everything she loves to get it. Poisoned livestock. Mysterious fires. And when armed men kidnap Sierra and her ten-year-old son, Rowan must confront the violent stepfather who drove him away to save the family he never knew existed.