On TV, relaying anything that has the merest connection to the internet isn’t easy, more often than not coming across like an uncle trying to talk about Drake. Generally speaking, TV is much better off pretending the internet doesn’t exist, in the same way that nobody on EastEnders is ever seen watching EastEnders. Overall, though, the makers of Cyberbully (Thursday, 9pm, C4) – which weirdly is billed as factual, presumably on the basis that everything that unfolds has happened to someone, somewhere – have got it right, on one condition: that it’s not viewed as a realistic depiction of cyberbullying at all, but as a kind of millennial ghost-in-the-machine spine-chiller instead, replete with traditional horror devices (Faustian pacts, anonymous ghouls, tests of morality), mild peril and creepy strings.

The first and biggest thing they’ve got right is casting Maisie Williams – Game Of Thrones’s Arya Stark – as protagonist Casey Jacobs. She is, obviously, entirely on point throughout, capturing all of the naivety, high drama and dismissiveness of adolescence, possibly because she is only 17 years old herself. There aren’t many actors whose immense talent makes it easy for a camera to hover on them for a full hour, give or take a few appearances from her pals by way of Vines or Skype calls.

Casey, who seems no more awful or wonderful than any other teenager, uses the internet as most teenagers do: equal parts pith and naivety. She makes derisory videos mocking vloggers and relishes the chance to hack into an ex’s Twitter account (“Erectile dysfunction makes me bitter. Please pray for me and my pathetic penis” – 10/10 for vengeance tweeting, there). Her online mischief is encouraged, it turns out, by the deception of an anonymous vigilante posing as a friend via instant message, who goes on to hold Casey hostage with the threat of uploading compromising videos and pictures lest she agrees to their every command. And all apparently with the aim of helping victims of cyberbullying, possibly the worst superhero MO since Unlawfully Parked Motor Vehicle Man.

Cleverly, it’s never totally clear whether Casey is the victim or the perpetrator. She’s likable, sardonic and sensitive (as evidenced by her supply of anti-anxiety medication, the very symbol of numb modernity), though some might view her derision of others as less than innocent, especially when it transpires that a fellow pupil whose karaoke video she mocked has been the subject of a widespread and vicious cyberbullying campaign. “If there’s one thing we all know it’s that everything gets slated online!” yells Casey in mitigation (and the girl really did murder that Katy Perry song). But the faceless crusader won’t let it drop, hounding Casey via every online device, and ultimately inviting her to, like, examine the monster within and shit – a favourite theme of Victorian gothic for anyone who thinks the fear of the phantom bleeding into our inner chambers only came about with those AOL 30-day trial CDs that peppered the 90s.

At times Cyberbully feels like a tug of war between the heavy-handed moral of the story and Williams snapping it back every time the drama strays towards the cringe, easily striding through any clunky allegorical flourishes where others would – to put it delicately – fall arse over digitally-rendered tit. If the aim here is to invite viewers to reassess their internet habits, I feel they’re on a hiding to precisely nothing: we’re all petulant bastards to varying depths and frequencies, and the grubby habits we carve out for ourselves only reflect that. But if the plan was to make an hour of drama that sends a chill down the mainframe then well done. That said, by the end, you just want Cyberbully to submit to the horror genre completely, add in a few (literal rather than metaphorical) demons, and have everybody murdered by someone in a Scream mask.