"Men Against Fire" was the most disturbing episode of the season. Army with AR implants for zero-empathy ethnic cleansing.
Later
Found it! Uncanny Valley:
I think this is both more plausible and more disturbing than "Men Against Fire". Also: the twist is less apparent --- for most of "Uncanny Valley" (if I'm remembering it clearly), you're not entirely sure whether it's a comment about how games generate dissipation the same way drugs do. "Men Against Fire" is predictable from about minute 10 (after the farm house scene).
Another "Black Mirror" problem I have: the episodes are way too long. "San Junipero" is the only one --- of all the seasons, I think! --- that earned its running length.
The morality lessons that the Twilight Zone oftentimes preached are manifested more as debates in Black Mirror with season 3, which I think is a lot tougher to write successfully. What is a bit of a letdown is that the debates are mostly contemporary (PTSD wasn't even a term when the Twilight Zone was airing) and will date this specific episode heavily. Meanwhile, most of what I watched in the Twilight Zone is still very relevant from even a thought experiment perspective.
I think I developed a lot more critical thinking watching Twilight Zone episodes as a child than anything I had to read in school.
"Who, after all, speaks today of the annihilation of the Armenians."
Edit Note: It is a very front-heavy(not sure what word to use there) episode.
Edit: I thought I'd add that that episode did take me two tries (I fell asleep during the boring part the first time, but watched it again 'cause I had faith inspired by every other black mirror episode).