Walker had an open phone line to Nazir, who was listening in on their conversation. Nazir asked to speak to Brody. He asked if it was true that the vest jammed. Brody said it was but that it may have turned out for the best since he could now be an inside man in the US Govt, especially as the Vice President was likely to become the President. Nazir thought this was a good idea, but that Walker was a fly in the ointment. He asked Brody to kill Walker to prove his commitment, which Brody did in short order.
Later, Brody spoke to Carrie to ask her to leave him and his family alone. Carrie was distraught, clearly believing she had it all wrong. She signed herself up for ECT (electro-convulsive therapy) to sort out her bipolar disorder.
Saul arrived at the last minute to try to talk her out of the therapy, saying that it wiped short term memory. Saul told Carrie that she was right - Nazir had been in a quiet period, owing to the death of his son Issa in the US drone strike. Carrie was determined to proceed with the ECT though. As she went under the anaesthetic, she suddenly realised that "Issa" was what Brody had been saying in his sleep when they slept together at the cabin. She had been right all along! She came round briefly and said something to that effect, which her sister overheard, but the anaesthetist said not to worry, that it often happened as people were going under. Then the ECT started (with some great acting by Claire Danes). The end ...