In Episode 9, called "Trade Secrets," we get an intriguing glimpse into the activities behind the rescue of Sgt. Bowe Bergdahl in 2014, nearly five years after he walked off his post and into Taliban captivity.

In this episode we learn that Bergdahl was one part of a much bigger, more complex picture of U.S. military operations in Afghanistan — especially foreign relations between the two countries and the labyrinth of diplomatic efforts going on at the time. We hear about the "fraught and fragile" diplomatic process and failed attempts at reconciliations and peace talks as far back as 2001. And we find out how it ended up that Bergdahl would be traded for five Taliban detainees at Guantanamo Bay.

"It wasn't a disaster and it wasn't a brilliant achievement. It was a successful and necessary operation, but it wasn't going to end the war," Jim Dobbins, who was the U.S. special representative for Afghanistan and Pakistan at the time of Bergdahl's rescue, said in the episode.

The episode poses the question of what Bergdahl's release to the U.S. meant in broader terms. Was it a tidy victory for the Taliban, who got everything they wanted for someone they were going to give up anyway? On the other hand, the U.S. had to get Bergdahl back somehow, was preparing to pull out of Afghanistan and needed prisoners out of Gitmo.

The next episode promises to delve more into what came next after Bergdahl's rescue: We're teased with a brief exchange about Bergdahl's parents being assured he wouldn't face serious charges and they probably wouldn't need a military lawyer. We know now, of course, that wasn't the case. So what happened in between?