After last week's episode, most people could have expected Lynne to die at some time during the season, as she couldn't be undercover forever and not get caught/leave. The writers one-up this by killing her off before this week's episode is even over, a twist that showed what was at stakes and propelled then show forward narratively. Through the course of the episode, we actually get a good look at Lynne and Carrie, and Lynne's death isn't a flippant killing as one may expect. Carrie cares about her job and she cares about Lynne. For Lynne to die so abruptly is a big deal and the viewers can feel that.
Alongside the spy story, Brody and his family remain very interesting, with the normal home life punctuated by odd behavior from Brody. We can see that there is something off with Brody, but besides from the more explicit flashbacks, we don't really know what's up with him. On top of that, Jessica is now trapped between her past and present--what she had with Mike and now her husband being miraculously alive.