In this era of NSA electronic snooping, the game goes on. In the 1970s, Le Carre fashioned the remarkable tale of a double agent in the British Intelligence Service aka MI6. This is not James Bond stuff, it's the real deal. The daily intel grind where nothing is as it seems (I'm borrowing from the text a bit).
After the 2nd World War, the Brits & Americans had to worry about the KGB in Soviet Russia. Le Carre takes us into the highest levels of spydome, Britain's "Circus" in London. The American CIA begins to wonder about "leaks" to the KGB. Turns out they were right. As a teaser, see the 2012 film "Tinker Tailor Soldier Spy" which I review separately.
Cutting to the chase, if you enjoy spy thrillers, you will want to read and own this trilogy. It will be with you for a long time.