Book Three of the Second Stage Lensman Trilogy, a series of authorised sequels to the original Lensmen novels by E.E. "Doc" Smith.

With Z-Lensman, the final novel in his post-E.E. Smith Lensmen trilogy, David A. Kyle turns his attention to the strangest of the three non-human Second Stage Lensmen: Nadreck the Palainian, whose Z-type species exists in a multidimensional state beyond the familiar three dimensions experienced by most of the galaxy's life forms. The constant shifting of their bodies through unfamiliar dimensions — together with the frightfully cold and poisonous atmosphere they breathe and their implacable emotional detachment — make the Palainians one of the more unsettling races known to Civilization. But, as events will soon demonstrate, they are also one of its most valuable assets.

In the process of training a new class of Z-type Lensmen cadets from the Palainian Z-Academy, Nadreck makes the unintentionally fateful decision to bring a religious leader from a Boskonian Spawn-influenced planet to be studied on Tellus before continuing on to Palain VII. On Tellus, Nadreck and the newly-promoted Galactic Patrol lieutenant Benson Cloudd become aware of a strange new problem affecting Civilized space. Machines throughout a wide swathe of the galaxy have begun to malfunction, and communicators, spaceships and computers are becoming increasingly unreliable. But in the process of searching for the source of this mechanical mayhem, Nadreck discovers something even more disturbing: remnants of the Eddorian Conspiracy are planning a new invasion, and their forces are gathering on multiple planes of existence!

Faced with mysteries and threats on multiple fronts, Nadreck, Cloudd and the android-bodied Lensman Lalla Kallatra must work together while at the same time scattering themselves across the stars, each in pursuit of their own piece of the puzzle. As the final confrontation approaches, all of the power wielded by Civilization — and all of the combined resourcefulness of its members, from Galactic Coordinator Kimball Kinnison personally leading the Patrol's Grand Fleet against an unprecedented weapon to the shade of Deuce O'Six defending the borders of the spirit world — must be brought to bear. But will it be enough? And will the threat that is closest to home be recognized in time?

All this and much more is revealed in Z-Lensman, the mesmerizing conclusion to Kyle's galaxies-spanning saga!

David A. Kyle's experience in Science Fiction dates back to the ''Golden Age'' of the early 1930s. An active force in both the earliest and present-day worlds of Science Fiction fandom, he began publishing fanzines as a teenager, and he participated in the first science fiction convention in Philadelphia in 1936. He attended the first World Science Fiction Convention in New York in 1939, and went on to chair the 14th Worldcon in 1956, and was Worldcon Fan Guest of Honor in 1983.

His professional career in the field spans six decades; beginning as a writer and illustrator for pulp magazines, then as publisher, anthologist, illustrator, book designer, editor, and literary agent. In 1947 he co-founded Gnome Press, the imprint that pioneered the first hardcover editions of works by such authors as Isaac Asimov, Sir Arthur C. Clarke, and Robert Howard.

He has collected an array of honors, among them First Fandom's Science Fiction Hall of Fame; a special award from the British Science Fiction Association; and an award for Outstanding Achievement from The International Society of Science Fiction, Horror and Fantasy. He has been chosen by Starlog as one of The 100 Most Important People in Science Fiction and Fantasy.

His works include the award-winning A Pictorial History of Science Fiction and The Illustrated Book of Science Fiction Ideas and Dreams.