The main story features Philip and Elizabeth half-way across America on a seduction mission of two separate, unmarried people. Although they're both pros at this, it's not as easy as it might seem. Philip's "marriage" to Martha left some scars on his psyche, and even the cooler Elizabeth, though she doesn't show it, is more affected than she would like or admit by these encounters.
Philip tries to get the two of them excused from this mission, but Gabriel won't have it. Significantly, their disguises make the two look even less like their real selves - especially so for Philip - than the disguises usually do. I think this is a deliberate, on the part of the show's producers, to show that it's more of a stretch for Philip than Elizabeth, and a stretch for both of them. Philip questions Elizabeth when she gets home, remarking that she seems to like her mark, She of course denies that, but the very question and her response shows their malaise about this part of their work. They're not exactly overjoyed about killing, either, but the lack of comfort with the dating is in some ways even more dangerous to their being as loyal spies.
Paige's continued movement towards spying herself is also of interest, and part of this story. As Philip and Elizabeth grow more unsettled about spying - especially Philip - their daughter is ever more eager to learn its craft and move into the field. There will no doubt be land mines ahead.
Meanwhile, Oleg in Moscow provides an important parallel, and a fascinating look into life in the Soviet capital in what we know will be its final decade (though Putin may be bringing some of that back now). And with Philip's son arriving in America, the bridge between the U.S. and Russia in this story is more active than ever, with lots of opportunities for unexpected collision and damage up ahead.
And see also The Americans: True and Deep ... The Americans 1.4: Preventing World War III ... The Americans 1.11: Elizabeth's Evolution ... The Americans Season 1 Finale: Excellent with One Exception