Hot Soldier Cowboy by Cindy Dees

Susan Monroe never, ever, wants to see her big brother’s best friend again. Small problem: a killer from her past has found her, and only the Blackjacks–including Special Forces operative, Mac Conlon–can save her. When Mac shows up at Susan’s ranch to take over protection duty, he hopes he can make amends for leaving her the way he did ten years ago. But Susan has grown up, and she’s having nothing to do with forgiving him. As a dangerous assassin chases them across the wilds of west Texas, Mac and Susan walk a fine line between life and death, love and hate.