‘If you were affected by any of the issues raised in this programme … ’ once ran the familiar coda to dramas before giving people barely enough time to scribble down the helpline number. Cyberbully is ready-made to feature such a post-broadcast message. But where previously people might pick up the phone when they seemingly had no one else to talk to about their problems, there is now an entire community on hand to offer either advice or pile on further agony. They’re just a click or two away.

This instant communication network is at the heart of this one-off piece, where lives can be changed forever (apparently rarely for the better) by an ill-judged or mean-spirited push of a send button. Maisie Williams (Game of Thrones’ intrepid swordsgirl, Arya Stark) plays Casey Jacobs, an all-too average teenage girl, cocooned in her bedroom amid a sea of social media. Before she knows it, Casey is drowning under the onslaught of an anonymous hacker who has taken over her computer, having retrieved and manipulated sensitive messages and videos that are set to massacre her reputation.

But there’s a twist to the tale: this seemingly callous cyber-stalker who is both spying on her through a webcam and talking to her via voice-disguised software might in fact be an avenging angel, putting Casey on the spot for her own abusive tendencies online. Although her tormentor describes himself (throughout we assume it’s a male stalker) as sounding like a ‘constipated Stephen Hawking’, Game of Thrones fans can justifiably claim him to be an homage to the sardonic Tyrion Lannister.

Cyberbully is set out like a modern conspiracy thriller, with Casey spending much of the hour trying to guess the identity of her internet menace (although describing it as ‘real time’, as Channel 4 has done, is faulty given that her dad announces he’s going out to the football only to return about 20 minutes later). But the whodunit element is a red herring, albeit a thoroughly entertaining one, as the real tension is racked up by seeing just how far our personal data can be used against us, should it ever fall into the wrong hands.

Cyberbully is on Channel 4, Thursday 15 January, 9pm

Cyberbully | Thurs 15th Jan | Channel 4