In The Capture, the conviction of Sutton soldier Shaun Emery for a murder in Afghanistan is overturned due to flawed video evidence.

But after damning footage from a night out comes to light, he finds himself fighting for his freedom once again.

Star Callum Turner, 29, tells Georgia Humphreys everything we need to know about the timely thriller, which asks: Can we really believe what we see?

HOW WOULD YOU DESCRIBE YOUR CHARACTER, SHAUN?

He's a famous guy - for all the wrong reasons. He's famous for being a murderer, and his initial journey is to clear his name, but also to change the way that the world views him. That's what he wants. But he's dragged back into another nightmare, that he can't get out of.

WHAT CAN YOU TELL US ABOUT SHAUN'S BACKGROUND?

Shaun's from Sutton in south-west London. He grew up working-class. He suffered a lot of trauma and a feeling of abandonment at an early age because his mum died when he was young and his dad died a few years later, so he was raised by his granddad.

As a younger man he's fallen in with a crowd and environment where there was a constant low-level hum of violence. I think it was a bit of a nothing-y existence, and he felt very frustrated, very alone, with no sense of responsibility.

HOW DID BEING IN THE ARMY CHANGE HIM?

When Shaun joined the Army, he found a family, he found a brotherhood, he found responsibility, he found a career.

He found adventure and purpose. Shaun was doing his job as he thought correctly in an active war zone, when he was caught on camera killing someone in a way that appears unlawful in the video evidence, and for this he's been reprimanded on a global scale amid a media storm.

Shaun feels abandoned by the Army, and that they've left him to fight the battle on his own, at which point he is drawn to human rights lawyers who decide that he hasn't done anything wrong and want to get him out of prison.

WHAT WAS YOUR OPINION OF SEAN WHEN YOU READ THE SCRIPT?

It's interesting how, when you do these things, your idea of something changes. I initially thought if you kill someone and it's against the law, then it's against the law.

But working with these guys [soldiers], it's your life or theirs. So, my perception changed, my ideas changed. And I have never been in that situation, so I don't know what it's like. So initially I was a bit stand-off, but then I found my way in.

TELL US MORE ABOUT YOUR RESEARCH FOR THE ROLE; WE HEAR YOU SPENT TIME WITH EX-SOLDIERS?

One in particular, Smudge - who was my trainer, but was then my friend - shared a lot of his experiences with me, helped build the character with me.

He showed me a lot of pictures on Facebook, which probably shouldn't be on Facebook, of soldiers being shot at and smiling, things like that, understanding how close they are to death.

But they're trained - these guys are killing machines. Trying to focus in on that and the energy of that person, that's the challenge.

WHAT DID THEY SAY TO YOU ABOUT HOW THEY'RE TREATED ONCE THEY COME HOME FROM WAR?

I'll speak generally... I think it's very hard for someone to come out of a service after 24 years, in which, amongst many things, it's a lot of fun. The brotherhood is so deep and entrenched that you can't get it when you come home.

Bags, who was another soldier I spoke to, was leading a squad and Christmas came up, everyone has leave.

No-one wanted to go home for Christmas, because, one, they don't want to leave their brothers behind, and, two, they don't want to come home and everyone's like, 'How are you? What's going on? What's it like? Are you OK?'

They just want to be back out doing the things that they're used to. And, also, the idea of going to Tesco's freaks them out - that's what they tell me. So being out there is better than coming home.

THE CAPTURE LOOKS AT THE IMPACT OF PTSD TOO...

They say that PTSD is not necessarily linked to any one thing, it's acclimatising to coming home. Because, the adrenaline... The bullets are flying, you're out and about, you're doing the job, it's life or death. And then you come home and it's like, 'I've got to go get bread'. It's not the same.

THE SERIES ALSO STARS HOLLIDAY GRAINGER, AS DI RACHEL CAREY. WHAT'S THE RELATIONSHIP LIKE BETWEEN YOUR TWO CHARACTERS?

It doesn't get off to the best start - Carey arrests Shaun in the first episode! This means that, at first, there's not much of a relationship, but things develop in a really interesting way where they have to work together in a way that doesn't quite sit well with either of them, because at the same time they can't quite trust each other.

The Capture starts on BBC One on Tuesday September 3