Since then, Homeland has kept relatively few secrets from the audience beyond the one that matters most in any TV show: what happens next. (The big exceptions being the details of Abu Nazir's plan and the identity of the mole many fans presume to be hiding in the CIA). With the recent apprehension and interrogation of Brody, the fog of suspicion for the show's characters had been in large part cleared as well. The central puzzle for Mathison—about whether Brody was working for Al Qaeda—had been solved. The question had become what to do about it.

But with "A Gettysburg Address," the people both on screen and watching the screen are back to guessing games. Is Brody really working against Nazir now? Carrie apparently thought so. Her unease at being told by Quinn to not trust Brody seemed to stem less from her stated annoyance at being talked down to than it did from some recognition that she indeed had started to trust him. In the episode's final scene, she melts down in front of Brody not just because of the horror of what happened in Gettysburg but because she suspects he may have known something about it. The hurt, as always, is personal: "Don't you lie to me, don't you touch me, don't you fucking dare," she spits.

Did you catch the moment when the show hinted it was reverting to its first-season storytelling technique? It's when Brody says that he's informed Roya that he'd been having sex with Carrie. We don't see that meeting with Roya—even though it seemed like we'd been, until that point, shown all the previous ones. And according to the protocol Roya refers to when Brody later intercepts her in the hallway, she and him only talk death-to-America topics when she initiates. So when he told Roya that he and Carrie "were fucking," Roya likely also told him something. And whatever that was, Brody hasn't passed it on to the CIA.

The far louder announcement that both viewers and protagonists have been plunged back into the dark came, of course, with the Gettysburg ambush. Who were those masked men? Their leader is the guy who Roya met with earlier—the guy who Galvez couldn't ID, who Max couldn't get a good mic on, and who Virgil couldn't trail into the Metro. (That opening sequence was not the show's best moment: It asked us to believe this relentlessly competent team fumbled a succession of seemingly elementary spying challenges. Also, what made them decide that this particular rendezvous of Roya's was the one that matters, when she presumably meets sources for her cover job all the time?) There's not a lot to go on for speculation at this point. The black-clad troopers could be shipped-in Hezbollah or garden-variety Abu Nazir operatives, but that feels too pat.

My wild theory: The killers are ex- (or possibly not-ex-) military whackos, like the ones busted for allegedly planning to assassinate Obama over the summer, who have struck an enemy-of-my-enemy kind of deal with Nazir's folks. That'd make some sense on a show that's so concerned with how war warps people, particularly soliders.