Amara (Emily Swallow) is all grown up and leaving a trail of bodies in her wake as she tries to find God.
The Winchesters strike a deal with Crowley, in the hopes that he can arrange a 'safe' meeting with Lucifer (a welcome return from Mark Pellegrino).
Crowley turns to his mother, Rowena, for magical assistance, and eventually she, Crowley, and Sam descend into Hell so that Sam can 'discuss' the Darkness situation with Lucifer, as his visions have guided him to.
Meanwhile, Amara 'kidnaps' Dean and tries to seduce him, explaining that God exiled her because he was jealous of her power to create a world of eternal bliss.
When it aired in the States, O Brother, Where Art Thou? was the mid-season finale and clearly there's a big effort here to move a lot of pieces into position for when the show returned, but still leaving things on a dramatic cliffhanger.
This means the episode is quite patchy. There's some great moments, but there are also some that drag on for too long.
The truth about Sam's visions was an interesting revelation, but Rowena's continued involvement in the main story arc still grates. Wasn't there a time when Crowley could do all this stuff for himself?
What we saw of Hell was quite atmospheric, and Amara's various conversations with people about God were a fascinating insight into her character, but her final moments in the episode were more "so what?" than "wow, what's become of her?".
At least we don't have to wait a month and a half to find out what happens next.