Meera Syal plays Miranda
Meera Syal plays Miranda, a private detective who is hired by Jackman's wife, Claire, when he leaves her without warning and she suspects he is having an affair.
"Miranda starts following Jackman and photographing him and it doesn't take her long to realise that there seems to be two different people – and she can't quite work this out," says Meera.
"When she stumbles across what's actually happening, she's absolutely fascinated by this incredible phenomenon and begins to get really involved in the case.
"Her detective curiosity makes her think this isn't just a job anymore; it's something quite extraordinary and she doesn't want to miss out."
Meera really loved Steven's script: "A lot of detective roles you read are a load of cliches. Miranda was such a different character and I really enjoyed her relationship with Min, not just because she's a lesbian but because the kind of banter they have is funny and fresh and rather Noel Cowardy.
"And they're also actually probably one of the happiest couples in the whole series! Miranda and Min's relationship is one of the spines running through the drama."
She describes Jekyll as: "A modern re-working of the old horror story but it's been given a completely different, contemporary and unexpected treatment with some really dark comedy.
"The very name 'Jekyll and Hyde' immediately conjures up images of strange noises and a hairy hand suddenly coming up behind you.
"But Steven has given it an incredibly modern, hi-tech twist. There's lots of scientific material in there – he's obviously done a lot of research, conjuring up a weird vision of the future."
Meera was delighted to be working with Jimmy Nesbitt: "He is a man who never seems to make a false career move; everything he does is very classy and he's a hugely talented actor.
"Obviously loads of people know him from Cold Feet, but when you see him in something like Bloody Sunday, you realise just how fantastic his range is. He's great to have on set as he's so upbeat.
"It seems to me that playing a part like that could probably get to you psychologically, but he didn't seem at all schizophrenic off stage – away from the camera he was quite normal!"
Meera also enjoyed working with Michelle and Fenella: "We had a real laugh. We spent a few days stuck in a van in the middle of a dark forest, so you get to bond pretty quickly and also Fenella was pregnant, so we were quite protective of her.
"Everyone felt very sad when we did our last scene as we all agreed it was so rare to do something which you think is going to be so good, where the crew are so great and you actually like everyone you're working with!"
She pauses: "Mind you, James did a really horrible thing to me early on. There was a scene where mid-way he changes into Hyde and has these awful prosthetic teeth and I hadn't seen them before.
"The director said: 'Right, just scream in Meera's face.' They said 'Action!' and he opened his mouth and screamed two inches from my face and I completely lost it – I screamed my head off and burst into tears and ran away in the middle of the shot and hid behind the crew! I can't tell you how terrified I was, because I was so hyped up. Everybody laughed at me, which I thought was quite cruel!"
Meera concludes: "I think Jekyll is going to be really good and different from what you usually see on TV these days. The way it's shot is so unusual and the script is so amazing. I'm desperate to see the series and genuinely think people will love it and be completely hooked."