"Then": Ruby got Sam addicted to demon blood after Dean went to Hell, and when Dean finally found out, he and Bobby locked Sam in Bobby's iron shelter for some de-tox at the end of the previous episode. Also, Castiel wanted to tell Dean something *very* important, but vanished. Anna, the rebellious "free willed" angel paid the brothers a visit and revealed that Castiel got "dragged back" to Heaven and disciplined by his superiors. After returning at the end of the previous episode, Castiel no longer was willing to share his secrets with Dean. The Angels' have told Dean they need him to stop the Apocalypse, but what are they *not* telling him?
This slow-burn episode has a lower User Rating than the previous "The Rapture", probably because it is less action-centric, but if not immediately, then after repeated viewings it becomes clear that this is the superior episode. What Sam goes through is extremely dramatic stuff, and Jared Padalecki rises to the challenge, delivering in every scene. Also, as we can see from the opening credits, Jim Beaver, Genevieve Cortese, Misha Collins and Julie McNiven are all here, preparing for the big season finale.
At this point, all the actors really have to be complemented, not only for their nuanced work in this episode, but all the way back to each one's first appearance. When the Apocalypse is indeed upon the characters, it is up to the actors to have made the viewers to feel for the characters, to invest in them. All the special effects in the world will mean nothing (like several End-of-the-World movies have proved) unless the viewer cares what happens to the characters. And we care. We care about Sam, Dean, Bobby, Castiel, Anna and possibly even Ruby, at least out of interest in her secrets. We cared about Pamela's death and we fear she won't be the last of the supporting cast to go. Actually, when this first aired, Supernatural was supposed to finish at the end of season 5, which meant that even Sam and Dean might not make it.
Lots of brilliant insight into the minds of Sam, Dean and Bobby here, but the angels and Ruby remain pleasingly ambiguous. It's not like in Lost, where characters who *knew* things did not share their knowledge, or worse yet, were not even asked what they know. Here, we know - or at least think we know - what the angels want, but not *how*. Ruby, on the other hand, has been seducing Sam to the dark side all season, Genevieve Cortese's performance greatly benefiting from the real-life chemistry she has with Padalecki. Anna, the only angel whose actions the audience can understand, has had very brief appearances except when she was introduced, but Julie McNiven has made the most out of them. Every time Anna appears, we get more and more convinced that what the angels are not telling, is something we should be very terrified of. Zachariah and Chuck's scene three episodes back confirmed it.
With a devastating final scene, this episode soars into the 9/10 Classic club, marking the point-of-no-return, paving the way for the season finale. And just like the best penultimate episodes of a season, it leaves us *needing* to see the big finale.