Christopher Eccleston’s new BBC drama The Shadow Line (BBC2, Thursday, May 5) is a dark and menacing cross between a murder mystery and a conspiracy thriller.

TV&Satellite Week magazine found the former Doctor Who star lurking in one of those anonymous London clubs that sit discreetly behind an unmarked door and asked him to explain what’s going on…

The Shadow Line certainly isn’t your run of the mill police drama is it?

“No, it’s got all the elements of a rip-roaring thriller, but it’s also a meditation on what it means to be human and what it means to be bad or good.”

That gives it quite a scope, doesn’t it?

“Yes, it’s a challenging piece. It’s as complex as a Swiss watch. Rafe Spall’s in it, too, and he and I would each read the script in between takes, just to try to work out what was going on.”

Can you compare it to anything else we may have seen on TV?

“Nothing recently. It’s not like anything else I can think of in the last 10 years. It’s very cinematic, but I have faith that there’s still a TV audience with an appetite for this sort of thing.

“It reminds me of Tinker Tailor Soldier Spy because of the time you get to spend with individual characters. It’s also got elements of Edge of Darkness about it. It’s the first time I’ve been involved in a BBC project of this size since Our Friends in the North.

“Although it’s a different animal from that, it approaches it in terms of its scale and ambition. I also thought a lot about Macbeth while I was doing it. But then I’m an actor. We think a lot about things like that. It’s what makes us pretentious.”

You play Joseph Bede. Although he’s in the heroin trade, he’s still quite a sympathetic figure, isn’t he?

“Audiences are going to struggle with how they feel about a lot of the characters, which is the way it should be. There are some moral criminals and there are some immoral policemen. It’s about human beings, we’re all half apes and half angels – which side are you on?”

So does Joseph veer towards the side of the apes or the angels?

“He’s an interesting character because of his moral blindness about the heroin trafficking he’s been involved in for 20 years. But he can’t step away from it because his wife has recently been diagnosed with early onset dementia in her mid to late 40s. She’s the love of his life and he needs a huge amount of money to make sure she’s properly cared for.”

Do you see yourself in Joseph at all?

“I can see his fearfulness in me. He’s in a nightmare. He’s losing someone he loves very deeply and at the same time he’s in a world he doesn’t relish. He finds it all terrifying and repulsive. I wouldn’t survive in his world, but what gives him his courage is his love for his wife and his need for money for her care.”

It is written and directed by Hugo Blick. Were you familiar with is work?

“I’d watched Marion and Geoff and hadn’t bothered to check who wrote or directed it. But when I started working on this I realised that in times to come Hugo will rank alongside the greats of TV drama like Dennis Potter and Jimmy McGovern.”

What was it like working with a writer who was also directing?

“It was good because for once I was in the fortunate position of having the writer and the director get along. But strangely when he was directing, Hugo would talk about the writer is if it wasn’t him. He’d say things like: ‘Oh, what a great line we have here in the script, don’t mess it up’.”

Does it feel good to be back on British TV?

“Yes, I like the pace of television and the immediate response of it. I like the idea of a nation sitting down together to watch something. British television made me an actor. It wasn’t film and it wasn’t theatre. Because of the way mum and dad brought us up, we didn’t watch the rubbish. We graduated towards the quality stuff – and not just the drama – we’d watch The Fall and Rise of Reginald Perrin, The Likely Lads, ‘Til Death Us Do Part as well as the Plays For Today. British television was my education.”

So you weren’t attracted by the idea of staying in US television after doing Heroes?

“Heroes was a big hit, but I never connected to it in any way. It didn’t mean anything to me. I was happy for the work and it was interesting to work in America. But engagement with my own culture is a very clear need to me. You can see that from the work I’ve chosen to do – things like Cracker, Hillsborough, Our Friends in the North and Hearts and Minds.”

You’ve done bits of comedy in The League of Gentlemen and Sarah Silverman’s show. Have you ever thought about doing more?

“I’m making concerted efforts to do more. We tend to deify serious acting. We think if you can play Hamlet, then you’re a proper actor. But comedy is just as difficult, if not more so. Great comic performers like Woody Allen, Peter Sellers and John Cleese are fascinating to me.

“I’ve shot a teaser comedy pilot with Jo Brand and Morwenna Banks called The Plot. We’ve only done 20 minutes, but I hope it comes off because there’s an opportunity for a really good comic monster in there for me.”