Few shows can pull of the difficult trick of executing a near flawless first season. Homeland, the acclaimed US spy drama, which starts on Channel 4 next month, is one of them. The twisty thriller, which stars Claire Danes as an on-the-edge CIA agent struggling to hide her bipolar condition and Damian Lewis as the returning war hero she suspects may be a terrorist plant, won widespread praise in America with the Los Angeles Times calling it "politically resonant, emotionally wrenching and plain old thrilling to watch" and The New Yorker branding it the "standout drama of the new season". At this month's Golden Globes it won best actress and best television drama, the latter award coming at the expense of much-hyped series such as Boardwalk Empire and Game of Thrones.
"We're still stunned by how well the show has been received," says Howard Gordon, who co-created Homeland with fellow 24 writer, Alex Gansa. "We knew it was good and that we had been lucky to get a great cast and a tremendous group of writers but we were never sure what the response would be because there was always a feeling that the country might be suffering from terrorism fatigue, that the last thing they would want to watch was a drama on this subject."
From the beginning, Homeland was marked out by its willingness to take risks. Taking as their starting point the acclaimed Israeli drama Hatufim, which followed a group of prisoners of war returning to family life, Gansa and Gordon spun a tale of conspiracy and paranoia that turns the thinking behind 24 on its head.
Where Jack Bauer's world was neatly divided into good and evil, a place where torture was justified in the name of the free world and heroism defined by the ability to laugh off pain, Homeland is predicated on the notion that trauma doesn't disappear, that good people can commit terrible acts, that there are no easy answers, no right side to pick.
"What we really wanted to do was tell a great spy novel on TV, a Graham Greene, John le Carré type story," says Gansa. "The sort of tale that was interesting and grey and compelling."
Greene and le Carré are pretty heady names to invoke but what allows Gansa and Gordon the right to do so is that Homeland is an unusually grown-up drama filled with half-heard conversations, subtle betrayals and the sort of plot twists that work because they feel true to the characters created.
"I think the thing about working on cable is we've been liberated from the conventional aspects of the thriller," says Gansa. "In particular, the idea that everything the hero does is good and everything the villain does is bad. It's not even always clear who the hero or villain might be."
It's certainly a world apart from 24 with its ticking clock and two-dimensional evil. Indeed, it's been labelled "24 for adults", a phrase that makes Gansa and Gordon laugh.
"Well, the whole structure of 24 was somewhat absurd, this idea that you have only 24 hours to save the world and that all this significant stuff could happen in that timeframe," says Gordon, who ran the show between 2006 and 2009. "It was built on hyper-realism."
What of the suggestions that 24 is a right-wing take on terrorist threat while Homeland approaches the same problem from a liberal or left-wing angle? Gordon, who describes himself as "kind of apolitical" is diplomatic. "They are shows written in a very different time," he says. "We live in a much more complex world with a new set of problems and a changing perspective. We have to write from that reality."
How close is Homeland to the Israeli original? "It's a significant departure," says Gordon. "The original show is solely about the prisoners of war and their return to their families. It's about how isolated these people who have been out of society feel. We took that as one strand and then added the thriller element."
Gansa interrupts. "We always knew that we wanted Homeland to be a thriller but what was interesting was the idea that you could tell a high-octane psychological thriller and also delve into the personal world of a family drama."
Crucially, in contrast to the last attempt at creating a grown-up spy drama, AMC's Rubicon, which aired on BBC4 last year, Homeland manages not to get bogged down in misdirection. Where the latter show seemed to be all twist and no resolution, Homeland boils down to one simple question: Is Carrie Mathison correct to believe that Sgt Nicholas Brody is a terrorist spy?
It's a testament to Damian Lewis's sympathetic but spiky performance that not only is the audience as unsure as the increasingly paranoid Carrie about the returning hero's motives, we also desperately hope he is who, and what, he claims to be.
"We looked long and hard at many actors before casting Brody," says Ganza. "Damian stood out not just because of Band of Brothers [where he played the upright Major Richard Winters] but because we'd seen Keane where he played a paranoid schizophrenic looking for his lost child. For the first 35 minutes of that film, he was pretty much the only person on screen and he was so compelling that we began to really consider him. There seemed a connection between the two characters."
The connection was damage. Like the titular Keane, Lewis's Brody is haunted by his captivity. Hailed as a hero, he feels increasingly unable to adjust to family life. Like Danes's Carrie he is desperate to make connections but unsure how to even begin.
And Carrie's dislocation is crucial to the show's uneasy dynamic. We might not trust Brody but we're equally unsure about the stability of the agent who orders him put under covert watch. "It was important to us that the main voice would be someone who would be the last person people in power would listen to, we wanted them to be this almost Chicken Little voice of paranoia, fear or caution, depending on how you look at it," says Gordon of the decision to make their lead a young, bipolar female agent. "We decided, well, they might listen to a woman less, a young woman in particular, and all the more so if that woman was hiding the fact that she's bipolar so that her behaviour is sometimes erratic. Carrie's record is extraordinary on one hand and yet spotty on the other and that adds an important dynamic."
More importantly, the bipolar condition, which Gansa and Gordon say they researched assiduously, never feels like an unsubtle plot device, thanks to an extraordinary, subtle performance from Danes who shows us both why Carrie is so good at her job and why she appears compelled to sabotage that success. Her Carrie is, as website The Awl adeptly put it, "a difficult, loud, excessively blunt mess of a person."
In other words, she's human. It's a humanity that both underpins the show and holds the key to its success. For Homeland is not a drama about good versus evil but rather a subtle look at the good and evil that we do, and the consequences, both big and small, that others pay for every careless act.
'Homeland' starts in mid-February on Channel 4