The pivotal action was between Frank/Black Jack and Claire. For the first time this season, we get a look at Frank's desperate and unsuccessful attempt to find Claire in 1945. And after he listens to a local's advice - which happens to be truth of the stones and their time traveling power - he almost does get to see and hold his Claire again. He hears her voice, as she hears his, on both sides of the time travel divide. But before they can reunite across time, redcoats pull her back to the two hundred years.
This lack of successful union is the theme of this episode, and it's played out again, totally in the past, when Black Jack is about to rape Claire on the table. Several important things about this scene. First, why is Black Jack so sexually attracted to Claire - because she's so beautiful, or is there something more? Surely a rape is not the best way to torture someone, as the fury it could provoke might well make the victim even less likely to talk. As for Claire, this is a dangerous scene indeed. She was just this close to reuniting with Frank. Will she feel nothing but hatred for the man who looks just like Frank, and is on the verge of raping her?
But that doesn't happen, either, because Jamie appears at the opportune moment as the episode ends. There is a nice mirror parallel in the Frank and Black Jack scenes with Claire. In the first, Claire is prevented from being with Frank by bad Brits of the past. In the second, Claire won't be raped by Black Jack because the best man in the past - Jamie - arrives on the scene to save her. When Jamie tells Black Jack to keep his hands and more off his wife, it's almost as if he's also telling that to Frank across time.
I've come to consider Outlander one of the best series on television now, and I'm very much looking forward to its resumption.
See also Outlander 1.1-3: The Hope of Time Travel ... Outlander 1.6: Outstanding ... Outlander 1.7: Tender Intertemporal Polygamy
podcast review of the first half season
Sierra Waters series, #1, time travel