On today’s show:

• The curious case of an ex-U.S. Marine locked in a Moscow prison. We spoke with Luke Harding who was interrogated in the same prison in 2007.
• Yemen may have made headlines for a devastating war, but Socotra island off the coast has been known to biologists for its biodiversity since antiquity.
• Critics of immigration policy often say they encourage people to enter the U.S. “legally.” That’s grown nearly impossible in recent years.