Lucas, Brock & Siobhan exact payback on a skinhead responsible for Emmett's death. Carrie faces new challenges in the wake of her revelation to Gordon and Deva about her past. Investigating the murder of four Marines, Lucas eyes the chance of a huge if dangerous heist.

In the opener of this "Manchurian Candidate"-like political thriller, a marine (Damian Lewis) rescued after eight years as a POW in Afghanistan returns home a war hero. But a CIA operative (Claire Danes) suspects he may actually be an enemy agent with a connection to Al Qaeda and part of a plan to commit a terrorist act on U.S. soil.

While Carrie and Saul are left reeling by the news that Walker is alive, the intelligence organizations squabble over how to capture him. The FBI leans toward using the public's help, but Carrie thinks they should use his family to draw him out. Elsewhere, Brody sets out to find a mysterious man who has surprising info about his years as a captive.

Having lost a number of essential personnel to Nazir's terrorist plot against the U.S., the CIA issue polygraph tests on everyone who had contact with them. This includes Brody, which Carrie hopes will reveal the truth about him.

An undercover DEA agent believes she is suffering from meth toxicity.