Sarah Koenig's popular NPR series Serial made its Season 2 debut today (December 10), alerting subscribers to its premiere episode via an email sent out early this morning.

Season 2 follows the mystery surrounding U.S. solider Bowe Bergdahl: Bergdahl walked off his post in Afghanistan back in 2009, only to be captured by the Taliban and held captive for five years. Last year, in a highly controversial move, President Obama agreed to trade five Taliban detainees from Guantanamo Bay in exchange for Bergdahl’s freedom.

Soon after Bergdahl arrived home, a debate began over the soldier’s unexplained departure from his post. While Bergdahl maintains that his intent was to reach another base to raise concerns he had about leadership problems within his own platoon, many labeled him a traitor.

The first episode, titled “Dustwun,” introducers listeners to Bergdahl’s story, some of which is told in his own words via a series of interviews recorded between him and screenwriter Mark Boal (The Hurt Locker, Zero Dark Thirty). Boal had originally expressed interest in turning Berghdal's story into a movie, and never expected the tapes to be released publicly.

Koenig, who narrates the podcast, said before agreeing to tell Bergdahl’s side she was a “very uneducated consumer of this story. But when I went back and read all the reporting, I was like, ‘Oh my God.’”

In addition to the new case, the second season sees a modified version of the series' popular theme song. Executive producer Julie Snyder said (via the New York Times), “We wanted to change it because the theme the first year really belonged to that story.”

Season 1 followed the murder case of Baltimore high school student Hae Min Lee, and the subsequent conviction of her ex-boyfriend Adnan Syed as the killer. Serial is credited with playing a significant part in the courts granting Syed another hearing to appeal his life sentence.

Listen to the first episode over on Serial's official website.