We live with the inability to fall asleep without a glassy black object nearby – you don’t need your phone when you’re going to bed, exactly, but you take no ease unless you know where it is. We lock our phones without a concrete reason besides the fact that letting someone else pick it up and look feels violating, too-intimate. It summons a nonspecific anxiety.

Game designer and critic Ian Bogost’s iOS-centric installation, at the Museum of Contemporary Art Jacksonville, aims to explore what the designer sees as a relationship between technology and religion; he likens the iPhone to a rosary, something we thumb automatically, observant. As a journalist on games I once craved the mainstreaming of designed interaction – now I startle to enter a silent subway car full of passengers with heads in laps, faces illuminated by screens, tapping.

The role of horror media in our culture is to show us our fears, to illuminate unspoken anxieties. Charlie Brooker’s Channel 4 series Black Mirror, something of a spiritual successor to The Twilight Zone, takes up the mantle for the digital age. Launched last year and now in its second season, it was inspired by the popular satirist and presenter’s own ambivalence to the increasing proliferation of these dark little screens; he found himself sincerely conversing with Siri (“a servile asslick with zero self-respect”), routinely performing the thoughtless tug-and-pop of Twitter refreshes.

Black Mirror's format is one I wish more American series emulated; rather than spooling shows into endless seasons of quick hits, it’s more common in the UK for quality TV to air robust, brief seasons. Black Mirror’s first season consists of three hour-long episodes, united by tone and theme instead of recurring characters or settings.

The third episode is called The Entire History of You, and it’s the one everyone talks about the most, with a sort of hushed dread (Robert Downey, Jr. reportedly optioned it for a film. Get the Arcade Fire to lend their song to the credits?). You ought not to watch it if you’re in a couple, they say, with a stricken look. This show has that kind of power: to rub your face in the viscera of everything about the modern world that you don’t want to think about. It is many things, but it is not pleasant viewing.

The boyfriend I’m in London to visit did not want us to watch The Entire History of You, which apparently involves a near-future where devices embedded in your body record everything you see, say and do – including your past relationships – for later viewing. In the browsing history of his iPad are several articles offering advice on overcoming jealousy of a partner’s past. He doesn’t know I’ve seen them, and he hasn’t told me about them; I know his mind from that black tablet.

The recently-aired first episode of season two explores just how much of a person can exist in the digital ether. It’s called Be Right Back, a play on the "BRB" notification people leave when exiting chat windows to go do real life.

A better title might have been Be Right There.

“Are we going to watch the new Black Mirror?” I asked my boyfriend.

“Be right there,” he said, immersed in a pretend city he was building on the iPad. I picked up my iPhone to kill time on Twitter until he was done.

“Are we watching it?” He asked ten minutes later. “Be right there,” I said. The irony of negotiating with our devices in order to watch a program about our relationship to our devices was pretty embarrassing.

Be Right Back is about a social media widow. Martha and Ash have moved in to a pastoral country house; Ash’s constant palming his stark black phone highlights the contrast between his social media use and the couple’s tactile life, framed in neutral tones with touching notes of green and turquoise. As characterization goes, Ash’s compulsion is wisely sketched with a light hand; he uses social media a lot, but not apparently dangerously so. No more than any of us.

The story begins in earnest when Ash is killed in an accident. A friend or relative–it’s not clear, as Black Mirror tends to place viewers directly into the flow of an episode without lavishing on background or irrelevant details –intrudes upon Martha at Ash’s funeral with an unsettling suggestion: There’s a new service that lets you talk to the dead.

Using the manifold digital fingerprints, photographs, voice recordings and text interactions he’s left in the social media space, this tech can serve Martha an interactive AI of Ash’s personality. It knows how he talks, his tastes and his memories – so long as he has shared them.

You can’t help but be gripped with the unease of wondering how much the black mirrors know about you. If it’s enough to resurrect you, how much of your essence have you divested onto the infrastructure? Twitter and Facebook obsess us with ideas about “sharing” and socialization, but is that really your life “on there,” or a thin, troubling simulacrum?

As we watch Martha, who learns she’s pregnant, succumb to her own grief-stricken urges to contact Ash’s memory through technology, the AI learns. It gains enough data to talk on the phone to her, and she reminds him of certain memories he’s meant to have, which he retains. When she nearly breaks her phone – and the increasingly-crucial lifeline, we feel her raw nerves.

We understand the ill junction of compulsion and disgust behind the mad, grotesque decision she makes next – a flickering car dash advertisement for synthetic body parts that we see  at the episode's outset foreshadows a key clue. The episode’s best moment is a lovely exercise in restraint: Martha waiting restlessly in her living room for what she’s wrought to leave the upstairs bathroom. The calm, gentle voice of the man she loves pleads urgently with her not to turn the light on.

I won't spoil the ending, but I’ll tell you it’s not the shambling Night of the Living Dead you’d expect of typical horror. It is more subtle, more gently terrible, sawing slowly at the heart like a dull knife. Martha’s “resurrection” of Ash ultimately suggests that the parody of authentic-self that we serve to social media is unholy, a violation.

Black Mirror’s gift is that it presents a world where anything is possible thanks to technology -- and prickles our skin regarding the inevitable complications of that possibility. We are ever on a quest for advancement, and it’s quite likely that we’ll figure out how to do things we’ll end up wishing we never learned how to do and cannot unlearn.

This is a show about our fear that some line may loom in the story of humankind that we ought not cross, for our own good. Such a line feels tangible, near; maybe we’ve even crossed it already. It is considered unenlightened and luddite to fear technology, but Black Mirror makes it startlingly easy to admit that there is much to be unsettled about these days, quietly, ambivalently.

The newest episode airs on Channel 4 on February 18. Brooker’s said it’s “not for the fainthearted.” I know, because I follow him on Twitter. Can't wait. Show is moreish.

Previously: Black Mirror is black, and it's brilliant - best sf on TV