At the heart of The Cardinal of the Kremlin is the enigmatic, courageous, stubborn, and remorseful Col. Filitov, who has been spying for the U.S. for thirty years. To the CIA, he is known by his code name Cardinal, and only a handful of top CIA officers know his true identity. He works as the chief aide to the Soviet Union's top military leader. His job is to study new military developments and offer advice as to the appropriate military response. He discovers the existence of an ultra-secret Soviet laser base in the mountains north of Afghanistan and passes on what he knows to the CIA, where it comes to Jack Ryan's attention.

The CIA is alarmed; the Soviets have already tested the laser apparatus—seemingly with success.

Filitov is a deeply troubled man who resists easy analysis. He knows that he is committing treason when...