Based on the Israeli version of "Prisoners of War." A U.S. soldier who was thought to have been killed in Iraq over 10 years ago who is now being questioned as to whether he is a member of a sleeper cell sent to cause a terrorist attack.
Sorry, no info about the next episode of Homeland is available yet.
However, our last information about it is this:
homeland.wikia.com, Jan 16, 2017: "Showtime renewed the series [Homeland] for a seventh season of 12 episodes on August 11, 2016. Season 8...will premiere in 2019. On January 16, 2017, it was confirmed that it will be the final season."