In attempting to answer the above question I thought about the espionage, the games and oneupmanship behind closed doors, the plausible and scary scenarios writer Greg Rucka often throws into the mix. But, truth be told, it all comes back to Tara Chace.
For those not in the know, Queen and Country is a comic book series (and three prose novels) that follow Tara Chace, an operative of the SIS (Secret Intelligence Service). The series described a number of Tara's missions as well as the subsequent fallout and political machinations surrounding them too. Over the course of the series Rucka not only fleshed out a great supporting cast for Tara, but showed us the effect such a life had on those that perpetrate it.
As Rucka explains in this awesome article over at io9:
"Tara can kill people with her bare hands and escape from Iran with two bullets in her body, but she can't maintain a personal life worth a damn."
This is before we get to everything else that makes the series great. We have the ever evolving roster of "Minders" (agents) and their changing dynamic with each other. We have their boss, Paul Crocker, a man of principles who is often tasked with breaching them, much to his disdain.
Queen & Country provides a stark, realistic look at the world of espionage-- more Len Deighton than Ian Fleming. It shows us the chicanery, the deals, the questionable ethics, the danger and the toll it takes on those who are constantly immersed in this world.
Have at it!