Apparently, young people use 'bitch' these days as a term of affection.

The young actress, Maisie Williams, who stars in Cyberbully (C4) worked with the scriptwriter in making its teenage dialogue more realistic.

She was able to tell him that some of his original lines didn't ring true, and that certain words had dropped out of fashion last year, or even last week, and that it's cool to address your best friend with a 'hey, bitch!'

But maybe the dialogue is just too authentic and in-your-face, as I was often irritated by the constant teen-speak. Cyberbully is a thriller set in real-time, and takes place solely in Casey's bedroom. We are immersed in her world and her language, listening to her phone or Skype her 'bitch' or reading the mis-spelled words she taps out in online messages and tweets.

Maybe the teenage world was created too well as I began to feel I was trapped in Casey's untidy, fairylit bedroom - which probably reeked of perfume and hairspray - as she chatted to her friends.

There was no adult input - and so no sensibly, grown-up dialogue - apart from her father calling to her from downstairs that dinner is ready, to which she sulks and sighs and shouts through the closed door that she's not hungry.

I began to feel a bit claustrophobic. I wanted out of this brat's bedroom!

Trivial teen concerns are discussed with her friend over Skype. Which music festival should they go to? Oh, did you see the nasty tweet your ex-boyfriend has sent? Oh, got a date with some guy now so gotta go!

Casey's ex, Nathan, has indeed tweeted something horrible about her, about how he's not surprised she's on anti-depressants because after one night with her he sure felt depressed. Is this it, I wondered? Is this the 'cyberbullying' the programme is out to portray? What a damp squib.

One of her pals pops up via online chat and offers to hack Nathan's Twitter for her so she can get revenge. He sends her a link allowing her to send a crude tweet in his name.

Some cyberbullying! When we all know of people who've been sent rape and death threats, this was weak stuff by comparison.

Then, everything changed.

The 'friend' who'd offered to hack Nathan's account is not who he said he was. He's an anonymous hacker and when Casey clicked the link he sent her, it gave him access to her computer, and to all her social media accounts and her private, intimate photographs.

Casey asks him what he wants with her. He says he helps victims of cyberbullying but she insists she's not a victim. He reveals he's acting on behalf of someone else, someone Casey had once trolled and who eventually committed suicide as a result of constant online abuse. Casey is the cyberbully, and the hacker is here for revenge.

The plots slides into horror as the hacker tried to goad Casey into suicide. One by one, he releases naked photos of her best friend, and says he'll do the same with Casey's pictures unless she takes an overdose of her anti-depressants.

He strikes a terrible deal with her: for every picture he refuses to release she has to take a pill. Casey sits by the laptop with her plastic carton of juice and her bottle of pills and starts to swallow them. One for each photo. A slow overdose to prevent her and her friend from being 'slut shamed'.

The hacker says if she closes down her computer or asks her Dad for help he'll upload all her photos and everything on her Dad's computer too, implying he's been visiting porn sites. One by one she takes pills, heading for a slow suicide, to protect the people she loves.

The drama's claustrophobic feeling was deliberate, suggesting that Casey too is trapped in her bedroom, not allowed to close the laptop and not allowed to seek help. Even though she's in the safest place on earth, the hacker can still reach her and prevent her Dad from intervening.

Only when the constant pills provoke Casey to vomit does her head begin to clear and she stumbles out into the hall where she falls to the carpet and shouts for Dad.

Ah, it's just teenagers, we might say. It's just Twitter. It's just chatter. Your child is safe upstairs in their warm bedroom and the doors are locked. What harm can come to them?