I've been speculating all week and am now almost beside myself.
My theory is this:
Brody was teaching Abu Nazir's son, Isa, to speak English. Then Isa was killed by a bomb.
OK what if Isa wasn't Abu Nazir's son? What if he told Brody that? The clip that keeps being shown, where Abu Nazir is watching the Vice President deny any American involvement, seems to indicate that's the moment that Brody turns, because he can see the Americans are lying.
What if he's actually looking at Abu Nazir and realises that he really is the enemy, after being seduced by his charm and friendliness? He realises that it's all a plot to make him, Brody, change allegiance? He loved Isa and realises that Abu Nazir has killed innocent children in an attempt to turn him.
So he plans a double bluff. He realises he has more chance both of escape and capture of Abu Nazir if he appears to turn. He comes back to the US a hero and plots a way of punishing those involved.
I don't think Brody is guilty of turning allegiance. I also don't think he's going to commit suicide. He is the hero and nobody nowadays in the West would see suicide for a cause as admirable. I also don't think Walker kills Brody. That would make Walker a hero of a kind and he's more of an incidental character. If Brody dies the message is either that troops can't be trusted or that heroes can be killed by villains.
As to who's involved within the CIA - I thought at first it would be Saul. Usually if someone's involved like this, they show their background, their home, etc. They did this with Saul. He has a deep sadness that would tie in with a cause, but I think essentially he's a good man.
David, on the other hand... We didn't see his lie detector results, did we? I will be disappointed if it's him as I think they could have rounded out his character, but I think it has to be, simply by process of elimination.
And Carrie - what a fantastic actress. When she's agitated, I feel agitated. I don't know about you, but the way I feel about her is the way her sister feels about her and I think that's very clever work.
So - what do you think will happen tonight?
BTW don't Google Homeland today as there is a site which seems to say moment by moment what happens. I didn't read past the first line but it didn't seem to be talking about past programmes. It must have aired in the US already.