No Quarter by Lindsay McKenna

Ukrainian combat medic, Alex Kazak joined Shield Security. One operator, ex-Marine Corps sniper, Lauren Parker, will have nothing to do with him. Thrown together on a mission to Peru, Alex’s old stomping grounds when he ran with a Russian team fighting Latin drug lords for turf and territory, Lauren tries to ignore his gentle and thoughtful charm.
Lauren’s tragic childhood comes back to haunt her as never before. Alex has fallen in love with the dynamic and courageous Lauren, and cannot understand why she is afraid of him when he’s never done anything but treat her with respect and admiration.
Little by little, Alex pieces together Lauren’s reactions toward him and it staggers him. He begins to earn Lauren’s trust. But is it too late? When Lauren is kidnapped by his old Russian team, there is only one of two outcomes: Lauren’s life hangs in the balance. Can he and a Special Forces team find her in time? His heart is shredded because he loves her and will do anything, including giving his life, to save hers.