It takes a while to spot what's sci-fi about Black Mirror's best episode

"Black Mirror" is known for dystopian visions of our tech-enhanced future. The episode everyone is talking about, though, is different.

"San Junipero" is the fourth episode of the Netflix-produced third season of the short film series.

Put it on and you may be struck, first, by the retro feel. Second, you may wonder what is sci-fi about it: the first act features no world-changing tech, only subtle hints in dialogue, music, and scenery that there's more than meets the eye. Finally, the ending is unlike any other in the series.

We've pulled highlights from the opening below. See if you can tell what's going on.