The Midnight Guardian — Sarah Jane Stratford

It's 1938, and the tentacles of Hitler's terrifying Third Reich have commenced their stranglehold on Europe. The Nazi empire will soon be clean of all bloodlines deemed tainted or undesirable...including vampires.
London's ancient tribunal of vampires is aghast at the destruction taking place on the Continent. Though vampires try not to interfere with human politics, Hitler's terrible plans force them into action. They resolve to send five of their most formidable vampires to Berlin -- millennials that have lived over 1000 years and whose age and wisdom make them close to invulnerable -- to infiltrate, disrupt, and destroy the growing Nazi war machine.
The brilliant and beautiful millennial Brigit is loath to go, but her powers are needed if the mission is to have any chance of success. She must summon all her strength to endure the separation from her lover Eamon, whom she made almost eight centuries ago, but whose lack of millennial status makes him an unacceptable choice for this operation. Though he longs to join her, his duty to Brigit is best served from afar, by nurturing their deep psychic connection and reinforcing her spirit with his fierce devotion and memories of his tender embrace.
But as the millennials attempt to penetrate and sabotage Hitler's armies, they discover that the Nazis are more capable than any human force they've yet encountered and more monstrous than they'd ever imagined. Forced to take bolder, more dangerous steps, they soon attract the attention of specially trained vampire hunters loyal to Hitler and his vision of a vampire-free Europe. Exposed, deep inside enemy territory, with vicious Nazi officers and hunters at her heels, Brigit must attempt a daring escape from the Continent, guarding precious cargo that marks the only hope of salvaging their mission.