Tuesday 3 May 2011: Fiendishly complex and morally ambiguous, The Shadow Line aims to bring HBO-style drama to the BBC. Amy Raphael talks to its creators about rebooting the cop show

It’s a ridiculously warm Saturday in late September, and Rafe Spall is sitting on a bench in Croydon cemetery, wearing a black suit, his face held up to the sun. Nearby, in a saloon car, Chiwetel Ejiofor and Kierston Wareing sit in protracted silence. Director Hugo Blick surveys the scene. He taps on the car window, motions for Ejiofor to open it, and leans in to give the two actors some notes.

Blick is writer, producer and director of The Shadow Line, a seven-part BBC crime drama that begins this Thursday. It’s stylised, intelligent and properly menacing. The criminals aren’t geezers – this is the absolute antithesis of Guy Ritchie – and the cops have no clear moral code. As Blick, who also directed Marion and Geoff with Rob Brydon, later says: “It’s a genre, a conspiracy thriller, but it presents the convention and then subverts it. The characters don’t end up where you might expect.”

Right from the start, Blick wanted to cast Ejiofor as Detective Inspector Jonah Gabriel and Christopher Eccleston as criminal Joseph Bede. Gabriel is an enigmatic, controlled cop who has a bullet lodged in his brain after a case that went wrong; Bede, meanwhile, has carefully built up a fruit and flower business to act as a front for smuggling heroin. The story follows DI Gabriel as he investigates a series of murders triggered by the fatal shooting of Harvey Wratten, a heroin importer. Ejiofor underplays Gabriel, allowing him only the odd outburst of emotion. Eccleston’s Bede, exhausted by caring for a wife with early-onset Alzheimer’s, wears his life on his face.

Blick secured his impressive cast by offering them demanding and perhaps unpredictable roles. Wareing, who plays the gutsy Sergeant Honey, acknowledges that she usually plays the character on the wrong side of the law (a prostitute in the BBC drama Five Daughters; founder of an employment agency for illegal immigrants in Ken Loach’s It’s a Free World). Lesley Sharp transforms herself into Bede’s bewildered wife. Spall proves himself a revelation as Jay, Wratten’s nephew, a creepy and disturbing idiot savant. More disturbing still is Stephen Rea, as the puppet master Gatehouse, apparently omniscient and prone to making threats in a soothing voice.

In a break from filming at the cemetery, Ejiofor is polite but distant, apparently still in character. Spall whispers that he has yet to tell Ejiofor he once sent him a fan letter after seeing him play Othello at the Donmar Warehouse in London. Blick, meanwhile, recalls a scene, shot some weeks earlier, between Rea and Antony Sher, playing old acquaintances. “They were in a clock shop, shooting an 11-hour day and neither of them fluffed a single line. Neither was going to give any ground. It was like having tickets for centre court.”

Actors raise their game for Blick, some because they are fans of Marion and Geoff, featuring Brydon’s desperately lonely minicab driver, or Sensitive Skin, his dark comedy starring Joanna Lumley. Others say they were genuinely excited by Blick’s script, which Eccleston says reminded him of Peter Flannery’s magnum opus Our Friends in the North. Spall admits to reading the script four times before fully understanding the intricate plot, and says that Blick’s drama “has no regard for the casual viewer. It’s event television. You have to lean forwards to work out what’s going on, but I think audiences like that.”

Blick’s characters are so well-drawn I imagine he stores their individual back stories on a Rolodex. He laughs. “Actually, there’s a big white board in my office that looks like a chemical flow chart or a double helix. That’s how I worked out the scandal at the heart of The Shadow Line.” So he has a mathematical mind? “Forensic, yes.” And intricate attention to detail pleases? “Yes. Although there is a great diversion between Marion and Geoff and The Shadow Line. The former was epic and forensically observed, too. It just took place inside a Mondeo.”

Blick says that when he first came up with the concept of The Shadow Line, he spent three months “deep thinking”. In particular, he thought about the “strange heroes” in Sydney Pollack’s Three Days of the Condor (1975) and Alan Pakula’s The Parallax View (1974). “Robert Redford gets all the information in Three Days of the Condor, but he can’t use it,” he explains. “Warren Beatty ends up getting shot in The Parallax View. Both were mainstream thrillers which ultimately revealed disquieting truths.” Blick liked the idea of Gatehouse turning up in the second episode, because it reminded him of Carol Reed’s The Third Man. “I had so many ideas. I wanted it to be a heightened story – it’s not of this world. The police have no logos or emblems to place them geographically. I wanted a Gotham-like quality. As Gotham is to New York, so the world of The Shadow Line is to London.”

Six months later, with filming over, we meet in an editing suite in Covent Garden, London. I expect Blick to be frazzled, but he is as enthusiastic as he was on set, showing me a car chase in which Ejiofor gets caught in a traffic jam and bellows, “Typical fucking British car chase!” He talks about his love of sound – you can hear the precise and oddly ominous crack of pistachio nuts being opened in one scene – and of Pinteresque pauses.

Inspired by Gotham City

We watch the very first scene: a black screen with two beams of light, two cops with torches walking through an apparently vast space. A man who turns out to be Harvey Wratten lies murdered in the back seat of an abandoned car. As the police poke about, there is no music on the soundtrack, no dialogue for at least a minute. It’s theatrical and sparse, and could alienate potential viewers. “You’re right,” he says. “It’s a difficult narrative way in. But if the viewer stays with us for six minutes – the length of that scene – then we think they’ll stay for the rest of the story. And, of course, the two beams of light represent the infinite possibilities of the story.”

I’m not sure the majority of viewers will pick up on every one of Blick’s ideas, but his “deep thinking” hasn’t got in the way of a good plot. Looking at some early episodes, the director pauses on a shot of Ejiofor having a tough conversation with his wife. “I wanted to make The Shadow Line completely colour-blind,” he says. “So often the race issue is something that has to be examined – we don’t go there. As an extension of the Gotham City idea again, we’re just not interested. Chiwetel, for example, could be anybody. It is, in fact, a very American idea.”

I ask Blick, who is surely a control freak, if he’s satisfied with the drama. He looks surprised at the question and almost shouts: “I am really happy!” Then he pauses. “Although there’s always a worry that perhaps if this came from America everyone would say it’s great, but because it’s from England it won’t be received as easily because it’s ambitious and complex.” I’ve tried hard not to mention The Wire – must all crime drama be compared to it for all eternity? – but Blick is not so disciplined. “If The Shadow Line came from HBO and had American accents, then British audiences would say, ‘Fuck me, this is good!’ He turns back to the screen, keen to get back to work. “This isn’t The Wire, but please don’t ask me to apologise.”