The Final Frontier (Star Trek: The Original Series; Movie Novelization #5)

The planet Nimbus III. A desolate, forbidding world, situated in the heart of the Neutral Zone. Unremarkable, except for one thing: Nimbus III is the site of an unprecedented attempt at cooperation among the galaxy's three major powers. Here, at this "Planet of Galactic Peace", the Klingons, the Romulans, and the Federation have all sent ambassadors, who are working together to develop the planet – an experiment that, if it succeeds, could transform the galactic balance-of-power.

But now terrorists have seized control of Nimbus III. And when Captain Kirk and the crew of the Enterprise attempt a dramatic rescue, they discover a threat unlike any they have ever faced. A threat that will force them to confront the inner demons of their own, secret pasts – and the forbidden secrets that lie at the center of the galaxy itself…