“Impossible. Could never happen. Think again.”

All episodes of Nightsleeper will arrive on BBC iPlayer at 6am on Sunday 15 September. Episodes will air on BBC One every Sunday and Monday from 9pm that night.

Nightsleeper is a real-time thriller for BBC iPlayer and BBC One. Created by BAFTA-winning writer Nick Leather, it is a six-part series in which a train is ‘hackjacked’ and driven through one single night from Glasgow to London on an uncertain journey. Part fast-moving heart-in-mouth action-adventure and part twisty-turny whodunnit detective story, it’s a roller coaster drama where no-one is ever quite who they seem.

Leading the fight are Joe Roag, a cop who is a passenger on the train and Abby Aysgarth, the acting technical director at the National Cyber Security Centre (NCSC). But who are they fighting? And how can they win against the self-styled ‘Driver’ who seems one step ahead of every solution?

There’s a small team working the night shift alongside Abby and a handful of passengers left on the train with Joe but are they all as innocent as you’d think? Who can they trust? Who can we trust? Are there people on board who know more than they are letting on?

Produced by Fremantle’s Euston Films for BBC iPlayer and BBC One, the 6×60 series is written by Nick Leather (Murdered For Being Different) and stars Alexandra Roach (The Light in the Hall) and Joe Cole (Gangs of London).

The series is executively produced by Euston Films’ managing director Kate Harwood, with Nick Leather, Jamie Magnus Stone and with Gaynor Holmes for the BBC. The series is directed by Jamie Magnus Stone (Doctor Who, Ten Pound Poms) and John Hayes (Dublin Murders). Created and written by Nick Leather with Laura Grace (Episodes 4 and 5). Producer is Jonathan Curling (The Sister, Baghdad Central). Co-Producer is Daisy Costello. Fremantle handles global distribution.

• Watch Nightsleeper on BBC iPlayer from 6am on Sunday 15 September

Introduction from Creator Nick Leather

One morning, a looooong time ago, I sat in front of a blank screen and tried to scare myself – technically and literally. What if I could find a journey that took six hours and stayed with it in real-time? Could I use it to create a contemporary locked room mystery? Where would I least like to be trapped? Who would I least like to be trapped with? Is there a way to be trapped that could only happen today?

I haven’t ever been trapped on a sleeper train from Glasgow to London, but I have been trapped on a broken down evening train from Newton-le-Willows to Manchester. For the first two hours, no-one spoke, we just grumbled and muttered to ourselves. But in the third hour, it all changed. One person started arguing with another about the volume of the music emitted by their headphones, others were pulled in, actually talking to each other as result. This wasn’t a thriller, although we were out of phone coverage and the toilet was out of order too, so it was not without jeopardy, but it absolutely was a relationship drama. In small ways, strangers revealed themselves, and – shock of all shocks in the digital age – actually connected in real-life.

If this became my real-time show, if a train were to drive off without its driver and we then followed it through the very heart of Britain as our heroes tried to prevent disaster, it could still be a relationship drama, whilst also being a conspiracy thriller. It could be an action flick, a disaster movie and a love story, all rolled into one. But really, it could be its own thing – it could be Nightsleeper. If our train was being driven by person or persons unknown, able to change first its route, then its destination, switch the points, get off the mainline and go somewhere else entirely… then what if the story could do that too? It could have twists and turns and heart and humour and humanity. It could entertain people and make them care and talk and gasp and tweet and laugh and cry and never ever be bored and absolutely, above all else, have to watch the next episode.

I pitched it to Kate Harwood at Euston Films – a few sentences at the end of a phone call – and immediately she was in. With her support, we got three people in a room to see if the premise was possible: a former government cyber expert specialising in critical infrastructure; a railway designer and train obsessive; and an “ethical hacker”. I half-expected them to stop the idea in its tracks. Impossible. Could never happen. Think again. What they said was much worse though. Not only could it happen, but – after a couple of hours of pooling their collective expertise – they decided they could almost certainly carry out a so-called “hackjack” between them. I was shocked… and a bit scared… and kind of delighted… and definitely exhilarated – all the things I want the audience to feel now watching our show.

From the moment we took it to the BBC, they’ve been completely supportive and I’ve never enjoyed working on a show as much, never loved a team as much and never seen one work with more joy and commitment. It has been the journey of a lifetime.

Please join us for the ride…

Interview with Alexandra Roach

Abby Aysgarth

What appealed about Nightsleeper?

When I read the scripts, I really could hear Abby’s voice, and I’ve never had that before. I loved how fearless she was. She’s working class with this spiky energy and I knew that I needed to be the voice of this character. She’s an underdog, while being in charge of this whole operation as Acting Technical Director at the National Cyber Security Centre, and I loved that contrast. I really related to that pressure of wanting to succeed, of having people around her doubt her and for her to prove them wrong. I wanted to step up and prove myself as well, I’ve been acting since I was a kid, the last 20 years or something, so to finally be given a chance to step up and lead a big BBC show felt like a big deal.

Was there a moment where you realised that leading a big BBC show would live up to expectations?

My first day of shooting, actually. It was a scene from episode two where Abby walks back into the office and stands up on the balcony, giving a speech to say to her team: Come on, we can do this! That was my first scene so my nerves as Alex were through the roof. I was thinking: how am I going to get over this? But I realised Abby would be feeling incredibly nervous and buzzy and she’d want to show everyone what she’s made of. So Abby trying to rouse them and inspire them? Most of that was just Alex saying: I’m here, I’ve arrived, I’m going to steer the ship as best as I can.

How do you sell the tech jargon?

Well, I know nothing about computers. Half the time I haven’t got a clue what Abby’s actually saying so you’ve just got to hope the writers have done their research and fully commit to it. If I didn’t, then we’d be in trouble.

How would you describe Abby?

When we first meet Abby, she’s about to switch her phone off, forget about everything at work and go on holiday with her best friend. It’s the first holiday she’s taken in years. She lost her dad a few months ago and has ploughed herself into work. She was first discovered by the National Cyber Security Centre, because she hacked into the system when she was a teenager and came to their attention as someone with potential. She was plucked out of South Wales and brought to London at an early age and trained in this stuff, and it’s become her life. Her work is almost her entire personality and she doesn’t really know who she is outside of that. Just as she’s at the airport about to check in for the flight, she gets a phone call to say: Hang on, there’s something dodgy going on, you might want to take a look. Abby has a spidey sense, she’s always one step ahead of everybody. She feels something’s not right and she needs to be across it.

Is she bothered about missing her holiday?

Oh, she does not want to go on that holiday – her friend is forcing her go. She feels more at home in that office with the computers and her team around her than anywhere. That’s definitely her happy place.

Did you do much research into Abby’s world?

I came on to this job pretty late in the game, but I spoke a lot to the writer, Nick Leather, who’s done years of research into it, and dived into certain podcasts about hackers and cybersecurity. It feels like something like this could never happen, but then you start looking into it and realise, actually this may be just one little step away. That fear we all have of the unknown, playing out in real time is going to be really unsettling for an audience, I hope. In the first episode, when the train starts moving on its own, it’s almost sci-fi and so unnerving. After this goes out, maybe people will bike to work!

Does Abby feel confident about handling the crisis?

She wants to present as confident, but she has an element of doubt within her, imposter syndrome that was something I really enjoyed playing. I brought my own imposter syndrome to it, really: she’s trained her whole life for this moment and she enjoys that pressure, but on the flip side, there’s a voice inside her head thinking: Am I the right person to lead this? Am I going to be able to save those people on the train?

As Acting Technical Director of the NCC, does she see this as a bit of an audition?

Definitely. That carrot is dangled in the first episode, which is all she’s dreamed off since when she was a little girl in South Wales. To have her own office, her own team, to be in this world that she understands, it’s so instinctive to her. She’s ambitious, but she’s fighting a lot of doubt.

What can you say about the relationship between Abby and Pev (David Threlfall)?

I love that relationship! He’s the one who saw her potential from a very young age and he’s almost become a father figure for her, especially as she’s just lost her dad. He’s seen by some as a wildcard, but she sees his genius and how his brain works – she understands it because she has it too, so they really get each other. She brings him in, much to everyone’s dismay and shock, but she trusts him completely.

Does Abby have any suspicions about who might be responsible?

She has to believe that it could be anyone. She thinks differently to everybody else in the cyber office – those guys fixate on someone and lose sight of the bigger picture, whereas she has an ability to see problems before they arise and keep an open mind. She can shape shift, that’s her sort of superpower.

How does her relationship with Joe Roag (played by Joe Cole) develop?

She likes him from the off. She trusts him and they share a sense of humour. There’s a scene where they’re singing a Kate Nash song together which shows their chemistry and shared perspectives. Although it’s a massive, scary situation, they just connect on a human, basic level, which becomes a real life-raft for them as the relationship is tested andsurprises and secrets come out about them both.

How did you find all the phone acting over six episodes of TV?

It was really challenging, and it’s rare to be shooting a show with your co-star and not actually see them physically. I was a bit nervous about how that would work, but I know Joe a little bit so that definitely helped. I came up with a system that worked for me, with an excellent Scottish actor John Scougall reading with me on set behind the camera. That was so helpful to have him there. That quietness and intimacy anchors Abby in the show and those moments feel like a bit of a haven within the confines of this crazy situation.

Would you like to play Abby again?

On the last day, I took her jacket off and hung it up and thought: please let me meet this character again and take her on another adventure. She made me braver. She stayed with me and she’s in my bones now.

Interview with Joe Cole

Joe Roag

How much fun was Nightsleeper to make?

A lot of fun. It was an interesting challenge because we were shooting in a studio just outside Glasgow. We were cooped up in these small carriages for 10, 12 hours a day and they’d pre-recorded the entirety of the train journey exteriors from Aberdeen to London on LED screens, which were outside the train. I’ve often been fortunate enough to work in real environments a lot, but this was all pretend, so it was a different way of doing things.

Could you see where the train was supposed to be in the UK while you were filming?

Yeah, although it was dark so you couldn’t really see much. They used it for the lighting in the windows on our faces a little bit here and there, which saves a lot of time in the edit and just looks better and more realistic. Although because you feel like you’re on a train, people were getting motion sickness if they looked out of the window for too long.

When you’re all confined for that long, how do you avoid going mad?

I actually thought it benefited the show. We’re all there all day together, all in the same green room with everyone running about changing mics and what have you, so you just couldn’t escape this absolute chaos. It was all part of the fun.

What does telling the story in real time bring?

An immediacy and an energy. Having seen the first episode, that clock ticking like Speed or 24 creates a tension.

Is Joe comfortable being a lone wolf or does he prefer working with people?

The whole show is about everyone doing their bit and working as a team to stop this train. Joe is a great leader of teams and a galvaniser of people although, at the beginning of this, he is a lone wolf. Gradually, he learns to cooperate and work with everybody else – he realises that if not everybody is on board, pardon the pun, then he’s not going to be able to stop the train.

Could you relate to Joe?

I tried to bring the fun, cheeky bit of myself to this role because a lot of the action heroes are just big hardmen with gruff voices. I tried to be free with it and play a real person, warts and all. I don’t have kids although I’ve got younger brothers that I’m very close to. Hopefully, the audience will try and put themselves in the shoes of the characters in the show and try to see who they would be within that group of people. We all want to hope we’d be the one that steps up and runs about and saves the day, but would we really? I’d like to think I’d be more like Joe in that moment, but that’s probably because I’ve done all these different movies so weirdly, I sometimes feel like an action hero.

When Joe first realises something is seriously wrong, does he feel equipped to react to the crisis or out of his depth?

He’s sort of figuring it out as he goes along. Obviously he has some skills and a basic level of training because he’s worked in police force. But this particular incident is quite far out of his field of expertise so he’s relying closely on Abby (Aysgarth, played by Alexandra Roach) at the other end of the phone to assist. They don’t have much time to figure out whether they can trust each other, they just have to get on with trying to get to the bottom of what’s happening. Joe grows into the role as the show goes on.

Could you talk about building that relationship with Alexandra?

It was about trying to create some rapport between myself and Alex Roach. I know her personally, but we never actually met for this because we weren’t in the scenes together. We were trying to create some sort of relationship over the phone, although I’ve just got someone reading in while I’m talking into a prop phone. It’s a different challenge when you can’t look somebody in the eye. You gain so much from somebody through their physical being and their eyes, because you can read their emotions non-verbally. When you’re on the phone, you sometimes have to perform a little bit more to create some energy. You can’t just talk in a monotonous tone.

Does Joe bond with any of his fellow passengers?

He bonds with the young kid Mouse (Adam Mitchell) because he reminds Joe of his own son, so we see some of Joe’s paternal qualities. One of the staff, Billy (Scott Reid), becomes quite useful, as do a couple of others with the more physical elements, and Joe uses one of the one of the guys on the train that knows the train well.

Was it fun to play off all those different actors in a small space?

Yeah, there are some amazing actors in that cast: Sharon Small, James Cosmo, Alex Ferns… Everybody brings something different, and they’re funny as well, so it was a joy. Hopefully, we’re creating a picture of what it might look like in the UK on one of these trains: ordinary people in an extraordinary circumstance having to step outside their comfort zone and save the day. That’s why I’m looking forward to it, because hopefully people in the UK will really be able to relate to these characters.

How do you feel about train travel now?

I had a stag do in Glasgow not long after the shoot and quite a lot of the lads got the night sleeper up there. I was like, Guys, do not get on that thing… I think they had a pretty rough journey and were knackered the whole trip. But it hasn’t put me off trains!