His Silent Vow by Maia Dylan

Kol never planned to fall in love.

Silence was his weapon. Control was his shield. And the Iron Covenant had taught him that attachment was a liability he couldn’t afford.
Until Eliza.

She was supposed to be a recovery mission—another woman pulled out of the dark edges of a trafficking network the Covenant was dismantling piece by piece. Instead, she became the one failure he couldn’t forget… and the reason he would burn the world to make things right.
Eliza Reed survived hell by staying invisible, by memorizing systems and patterns, by turning her mind into a fortress no one could break into. When the men who bought her thought they owned her, they underestimated the one thing she refused to surrender: her will.

When Kol finds her, she is bruised, silent, and dangerous in ways no one sees coming.
As the Covenant hunts the men who sold her—and the powerful figure who believes himself untouchable—Eliza steps into a new kind of fight. One where intelligence is deadlier than bullets, and truth can bring governments to their knees.

Kol doesn’t save her. He stands with her. In a world built on secrets, violence, and betrayal, love isn’t loud. It isn’t rushed. And it isn’t promised lightly. But some vows don’t need to be spoken to be unbreakable.