The Fourth Protocol features renegade elements within the Soviet Union attempting 
to plant a nuclear bomb near an American airbase in the UK. The motive for this can be found in a plan hatched by Kim Philby in his Soviet exile, to control British elections and the British premier. The book was filmed in 1987, starring Michael Caine and Pierce Brosnan. However, the book is better than the movie!
The Fourth Protocol takes a little while to shift into high gear (about one third of the way), but when it does, it really rocks. It is a great read, some think perhaps even the best of Forsyth’s books. Even though it is not on the absolute top for me, the plot is intriguing, the action is thick, and the characters believable. And, it is, of course, well written.