Season 2 of top podcast "Serial" launched Thursday, shifting gears in both subject matter and delivery.

The latest season investigates the story of Sergeant Bowe Bergdahl, a U.S. soldier who left his post in Afghanistan in 2009 and was captured by the Taliban.

He was charged with desertion. The high-profile case is a departure from the first season, in which narrator Sarah Koenig unfolded the tale of an obscure murder in Baltimore.

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It also is the first time "Serial" has expanded its distribution to a streaming service. The series will stream exclusively on online radio provider Pandora, which has about 78 million listeners.

"Serial" will also be available on the podcasts own website and through Apple's iTunes store. The Pandora streams run with ads for Warner Bros. Pictures and Village Roadshow Pictures' "In the Heart of the Sea" and Esurance.

"Serial" was a full-blown cultural phenomenon. It reached 5 million downloads and streams on Apple's iTunes store faster than any other podcast, according to the gadget maker, and revived interest in the a format named after a device — the iPod — that has largely been relegated to history.

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Sales of iPods have dwindled to such meager levels that Apple doesn't report them anymore.