Aside from the season premier when the stage was beautifully set, this episode is the epitome of "and the plot thickens". I was disappointed with last weeks episode and felt that the entire episode was filler with lots of flashbacks and a stale story that didn't forward the main narrative, with the exception of the last minutes and the big reveal.
But this episode is non-stop edge of your seat suspense. Without giving anything away, the writing for this episode was bold and sharp with a lot happening, probably more storyline added to the narrative than the last three episodes combined. Even better, certain side-stories I felt lacked clarity and/or had plot holes in them pretty much all got filled in and explained. You know an episode is great when you not only can't wait for next weeks episode, but get angry you actually have to wait an entire week for it. Hoping this great writing with reveals continues until the season finale.