Cyberbully, Channel 4, 9pm

At 17, Maisie Williams has probably achieved more, seen more than most of us will in a lifetime, yet the star of Game of Thrones remains a remarkably modest, unaffected young woman. Here, she discusses her new project, Cyberbully, a one-off drama about the dangers lurking on the internet.

You play Casey. What’s her story?

Casey begins as a young teenager who’s struggling to express herself, and the only way she feels safe is to do that anonymously through the internet. She finds that, using a fake name, she can post honestly about things that annoy her, things that make her laugh, things that make her happy and sad. As the story picks up, she realises that, through hacking and whatever, people can take anything and they can turn it into something you never meant it to be. Even the nicest and most genuine of people can be portrayed as something they’re not.

What was it like to film this project?

It’s been one of the most intense two weeks of my life. I’ve thoroughly enjoyed it, but it’s come with its difficulties. Teenagers are written pretty poorly, and this was such a good representation of a normal teen, who doesn’t have some extreme family issue or mental issue, or is a drug dealer or something.

The story is pretty frightening, in terms of how much a person can destroy someone’s life. Is everything that happens genuinely possible?

Yeah, of course. There is no one story that Cyberbully is based upon, but everything included is very much possible, or has happened to various different people.

Has it made you think about internet security and what you do online?

Yeah, definitely. I think people always assume that it’s going to happen to someone else. But in America, for example, everyone always puts a sticker over their webcam, little things like that, which really makes you stop and think. It’s something we’re all very new to.You think something’s safe just because it has a password on it, but that’s not always the case.

Being on Facebook and Twitter and stuff have you experienced negativity and trolling?

Yeah, of course. Trolling is the biggest thing that anyone faces, and it’s easy to dismiss, but it does hurt. As much as we like to say we don’t care, of course we do. People laugh at me when I try to stop people from behaving like that. Just in my followers, not on the internet in general.

Sixty-nine per cent of young people say they’ve experienced some form of Cyberbullying. That’s an extraordinary statistic, isn’t it?

Everyone I know is on Facebook, and if they’re not it’s because they’ve had a negative experience with it. That’s just awful. People turn a blind eye to stuff like that until someone goes too far.

One of the things that struck me about the script is that Casey has inadvertently done a bit of cyberbullying herself.

You need to ask yourself “Would I be happy for my mum to see that I’d just written that?” Just because you’re hiding behind a fake name doesn’t mean you’re not talking to real people.

Your first professional acting role was as Arya Stark in Game of Thrones. How has your life changed in the past few years?

Completely. But it’s like I’ve never known anything else, really. I was a child, and then I started doing Game of Thrones, and now all of a sudden I’m growing up, I’m nearly 18 and I’m nearly officially an adult. I’ve been so lucky to have been given the opportunity to do something I love for the rest of my life.

What one message would you want young viewers to take away from the drama?

Some people on the internet are never going to be satisfied with any reasoning. The answer is just to close your computer and walk away, because it doesn’t matter. Don’t try reasoning with the trolls or the bullies, don’t engage with them, just walk away. You can’t win, so just walk away, and find people who really care about you.