IN A CAMOUFLAGED frontier observation post in Europe, British Secret Service chief Goss waits for the prisoner exchange to begin. In return for his prize catch, whom the British tabloids have labeled "the spy of the century," the KGB is returning Goss' agent Conroy. The spies pass narrowly on a high bridge. So begins N.J. Crisp's taut thriller, The Brink.

In a superbly plotted and crafted novel, Conroy returns to England to find himself under suspicion. Was he really caught by the Russians, Goss wants to know, or did he turn himself over to them on purpose? In other words, is he a double agent? Or is the double agent Conroy's spy girlfriend? Or, if you look at it from Conroy's point of view, is the double agent Goss?

The two lovers and Goss try to trick each other, trap each other. It looks like one will die. But this plot of triple betrayal goes far beyond the personal danger involved. Set in the very near future, the Soviets face NATO across a nuclear firebreak. The answer to who- fingered-Conroy is tied to the fate of Europe.

The novel's buildup is measured, the payoff rich, the stakes a communist puppet Europe. From a depressingly credible depiction of the decline of the West, N.J. Crisp has come up with a technological turn of events to explain the greatest Soviet gamble since the Cuban missile crisis. The backdrop: the anti-nuclear movement in Europe.

There is something in this book which brings the threat of nuclear annihilation close. Studies have labeled Americans as anesthetized to the concept of such a war. The possibility is so deadly and immediate that people assign it to the realm of the theoretical. I have a friend who commutes to Rockville each day to plan where to send doctors if war begins. Her job brings the closeness of war home in a way novels generally fail to, but The Brink made me afraid and even morose. Yes, the plot is well worth the read, but the specialness of this book is that extra awareness.