The BerlinBrigade.com Book of the Month for January 2013 is Voices Under Berlin: The Tale Of A Monterey Mary by T.H.E. Hill.
This is a great story that will give you a fictionalized and unique insider's view of how things may have happened in 1955 Berlin's Spy Tunnel. While it may be hard to imagine how things such as this were going on beneath the feet of the citizens of Berlin but it was the Cold War after all.
From Amazon.com: Dr. Wesley Britton, author of "Spy Television", "Beyond Bond: Spies in Fiction and Film", and "Onscreen and Undercover: The Ultimate Book of Movie Espionage", writing at SpyWise.net writes "Throughout the Cold War, the divided city of Berlin was the epicenter of spy films and literature, especially in the hands of masters like John Le Carré and Len Deighton. For decades, we saw and read about Western agents sneaking in and Eastern defectors sneaking out of East Berlin--over, under, and through the most iconic symbol of the times--the Berlin Wall.
But T.H.E. Hill's new 2008 "Voices Under Berlin: The Tale of a Monterey Mary" has nothing to do with such spy vs. spy duels in Germany. Instead, his subject is the long-neglected Berlin Tunnel of the 1950s and the cryptographers, linguists, and analysts sifting through intercepted intelligence from East Germany to the masters in Moscow. Better--Voices Under Berlin is, in fact, perhaps the funniest spy book ever written. It's not a parody or satire of the 007 mythos nor is it a continuation of themes in the novels by the likes of Graham Greene or Eric Ambler poking fun at the ineptitude of clandestine services. Still, in the tradition of Greene and Ambler, Voices Under Berlin contains many literate qualities that make it a work of special consideration, worthy of an audience much broader than that of espionage enthusiasts or those interested in Cold War history."
You can order your copy of Voices Under Berlin by T.H.E. Hill: