Viewers will see a changed Peter Quinn (Rupert Friend) when the award-winning political thriller series "Homeland" returns for its fifth season.

Executive producer Alex Gansa revealed to TV Guide what happened to the agent after leaving no clue about his whereabouts at the end of the last installment. Quinn was last seen when he urged Carrie (Claire Danes) to run away with him and leave the CIA together. When she turned down his offer, he appeared to have vanished into thin air.

What little fans know about him was from Dar Adal (F. Murray Abraham) after Carrie questioned him on where Quinn went. The agent gave her a vague answer, saying Quinn had left for some secret mission, and he was not sure if Quinn went to Syria or Iraq.

Gansa disclosed that Quinn was actually leading a mission in both countries, and this somehow took a toll on him, changing his personality.

"Quinn will be a different character this year. He spent a couple years down in Syria and Iraq leading a special forces team. You can imagine the stuff he's seen and how that might affect him," said Gansa.

Meanwhile, in a teaser released by Showtime, Friend discussed his character's stint in the Middle East and his partnership with Saul Berenson (Mandy Patinkin). According to the actor, Quinn and Saul have struck up "a very special friendship;" but that it was a bond no one can know about.

"There is no one on this planet that Saul would put more trust and faith in than Peter Quinn," he said.

As it is, Friend also revealed that a happy reunion with Carrie was the farthest thing in Quinn's mind. His character was apparently turning into "a much more brutal soldier" and would remain so for most of the season.

"I think Quinn's given up all pretense of a normal life and finds that idea ridiculous," said Friend.

"Homeland" Season 5 will premiere on Oct. 4 at 9 p.m. EST on Showtime.