Grey's book sheds light on the clandestine air traffic behind the U.S. government's detention and rendition programs. Not surprisingly, the Guantánamo Bay base has been convenient stop for U.S. government "ghost planes."
When Guantanamo Bay opened up, someone at the CIA told me that Guantanamo was just the tip of the iceberg-- that there was a much larger network of prisons, jails around the world associated with the rendition program.
But the question becomes how to investigate this, given its immense secrecy. An opening occurred when I heard of one plane involved in the rendition from Sweden. Then the trail was picked up. I found my own "Deep Throat" who could provide me with flight plans of the CIA jet, and then I was able to identify a fleet of planes, and could trace their involvement. The story, in fact, became following these planes, because with this data, we could prove (1) that the stories of renditions told by prisoners who were released or got lawyers at Guantanamo were true, as their accounts matched flight plans precisely, (2) by looking at a fleet of aircraft, we could show that it was the CIA itself doing these things, and (3) I spoke to some of the pilots, who confirmed that they in fact worked for the CIA.