Starship pilot Terry Radnor is elated to be among those chosen to defend the secret colony Maclairn against enemies who pose a threat to the spread of paranormal human mind powers. He commits himself wholly to the goal of that world, not guessing how far his effort to protect it will take him from everything else he cares about—his promising career as a Fleet officer, contact with people who share his newly-discovered psi capability, his wife and unborn child. Torn away against his will after learning a secret too deep for its disclosure to be risked, he is forced into exile from all that has previously mattered to him, and must build a perilous new life far from Maclairn, grounded without hope of fulfilling his earlier pledge. Yet a mysterious and extraordinary destiny has been predicted for Terry, and against all odds fate puts him in place to confront the colony's greatest peril.

This is the first book in the Captain of Estel trilogy. While it follows the Founders of Maclairn duology consisting of Stewards of the Flame and Promise of the Flame, it is a completely separate and quite different story set two hundred years later that does not depend on having read them. Though intended for adults, the trilogy will also be of interest toPolder teens who have enjoyed Enchantress from the Stars and The Far Side of Evil, since its second and third books deal in part with the Service that appears in those novels. (Please note that unlike Engdahl's YA novels, all five of these books contain some material inappropriate for readers below high school age.)

From the reviews:

"This book reaches back to the brio and speculation of Engdahl's classic books of the Seventies. . . The reader will be taken on an exciting and suspenseful ride. . With an admirable protagonist and many interesting and well-drawn characters major and minor, Defender is satisfying on multiple levels. . . I expected to like this book; I was startled that I loved it. A must read." —Literary critic Nicholas Birns

"These novels [this book and its sequel] are not so much genre ... 'Science Fiction' as they are Literature. These are novels about life." —Jacqueline Lichtenberg, Alien Romances Reviews 14