Showtime is beefing up the acting armoury of its Emmy award winning drama Homeland with the announcement of additional cast in season 3, including Joana Merlin, Nazanin Boniadi, Amy Morton, Lawrence Clayton and Tracy Letts.

Morton is set to play a recurring role Erin Kimball, the appointed CIA attorney to Carrie Mathison (Claire Danes) in view of the events that transpired in season 2. Joanna Merlin (Law and Order: SVU) will be Grandma Lois, mother of Jessica Brody (Morena Baccarin).

Boniadi will take on the character Fara, who despite her youthful appearance will portray the role of an expert analyst, and Gary Wilmes as Dr. Richardson, a psychiatrist who will provide help to Dana Brody (Morgan Saylor) in dealing with recent events. Sam Underwood will appear as Leo, a man with a troubled past who will become a new friend to Dana.

In the shocking finale of Homeland season 2, viewers saw Nick Brody (Damian Lewis) bidding Carrie goodbye as he was setting off for Canada. With the horrible label now hanging over his head, will Nick still want anyone to see him again?

Showtime has released Season 3's official synopsis, erasing all questions on who the country blames for the attack on CIA headquarters last season. The third instalment opens "during the aftermath of the horrific terror attack that decimated the U.S. intelligence apparatus, and prompted a global manhunt for the world's most wanted terrorist - Nick Brody."

The new season also finds Carrie and Saul (Mandy Patinkin) attempting to rebuild their personal and professional lives amid the political and media firestorm surrounding the terror attack, and the search for Brody's whereabouts.

In the aftermath of the events in season 2, viewers will see the government digging into the terror attack more deeply. According to Showtime, those who will be seeking answers include new cast additions Letts (Prison Break) who'll play as Senator Andrew Lockhart, the mighty and commanding committee chairman, Clayton (Dreamgirls, The Big C) as Admiral Jim Pennington, the National Security Advisor of the President, and Pascal (Graceland) as Majority Counsel David Portillo, a member of the Senate Select Committee on Intelligence.

Rupert Friend and Jackson Pace also rejoin the cast in Season 3. Homeland season 3 premiers on September 9.