I just had to contribute this. I'm currently reading Child 44 by Tom Rob Smith. The first 100 pages were so good that I went straight on to Amazon to order his second book, "The Secret Speech." I honestly think that nobody has produced a book like this before.
It concerns an investigator in the Soviet Union's MGB (forerunner of the KGB) during the era of Stalin's murderous reign. It is the time when the state maintained that if you were accused of subversion you must automatically be guilty, otherwise you wouldn't have been accused.
Leo Demidov is the agent who is growing disillusioned after interrogating a suspect he is convinced is innocent but is subsequently executed.
Simultaneously, a serial killer is murdering children at widely scattered locations. However, communism maintains that crime is a result of society's failure. Since the Soviet Union is a perfect society, serial murders can't possibley take place.
And then Demidov's wife is accused of espionage and Demidov is ordered to investigate his own wife and report back to the MGB.
This book is such a page turner that it's agony each time I have to put the book down. Recommended very, very highly.