Based on an Israeli series called Prisoners of War it had an amazing opening hook with an American soldier (Damien Lewis) coming back from being captured by al-Qaeda to a heroes welcome in the USA. Only a bi-polar analyst (Claire Danes) believes that he might have been turned by the enemy.
That was plenty of fodder to begin with but the show has gone off the rails a bit since then, losing the clear focus which it had at the beginning. Still Showtime has faith in the production, recently renewing it up for seasons six, seven and eight to bring it up to at least 2019.
Now Deadline reports that we might be seeing the end of the story. They were chatting to showrunner Alex Gansa at the 2016 Emmy's (where it didn't win any of the three nominated categories) and said that he planned to wrap things up by the end of season eight.
It's far from definitive at this point, with only Gansa suggesting he's done with the project then. Showtime might decide to continue, or maybe even pursue the story in an entirely different direction. To our minds, eight seasons will probably be more than enough.