Guardian of the Night (The Specialists)

the long version

Former military intelligence officer Noah Drake exiled himself to a small island off the coast of Georgia after the side effects of an untested drug destroyed his body's tolerance to light. But because of his sacrifice, he brought down a dangerous traitor. Now, five years later, Noah's adversary is back to settle the score. The man moved as stealthily as a shadow, but Specialist Maggie "Blue" Callahan had her assignment -- to protect Noah at all costs. And no matter how much Noah protested, she would carry it out. Except that was becoming increasingly difficult with the seductive siren call of the night. Would its inexorable rhythm sentence them both to the all-consuming darkness?