It's about WWII spies. The central thread is a plot by English counterspies to fool the Nazis into thinking that the invasion of Sicily would actually be an invasion of Greece and Sardinia. It's a gruesome plot: dressing up a corpse as a military courier, planting forged documents on it, then dumping it into the Mediterranean so that it will wash up on shore and be discovered. Along the way, there's a submarine, a maze of bribery and corruption, and plenty to worry about.