How do you follow one of the most acclaimed cult shows of recent years? A programme that is not only considered the best teen drama ever made but is also still mourned on sites across the internet, taught as a seminar subject at universities and fervently discussed at academic and sci-fi conferences alike. That's the problem that has been occupying Joss Whedon since Buffy the Vampire Slayer finished in 2003. Post-Buffy, Whedon has bought us Serenity, the movie sequel to his short-lived space opera Firefly, which ran for 14 episodes in 2002, and internet sensation Dr Horrible's Sing-Along Blog, which saw How I Met Your Mother star Neil Patrick Harris ham it up as a super-villain in love. Now the man who gave vampires souls and teenage girls wit has returned to the small screen with Dollhouse, a sci-fi drama about a mysterious agency whose employees have their personalities wiped between assignments, allowing them to be imprinted with a new persona, based on that of a existing person, for each job.

Focusing on former Buffy bad girl Eliza Dushku's Echo, Dollhouse begins as a fairly straightforward procedural, even down to having a different story each week. However, this being Whedon, things aren't quite as straightforward as they seem. For a start, there's the fact that the employees, or dolls, aren't simply working to solve crimes but can also be hired out as anything from romantic partners for love-starved businessmen to, as in the first episode, negotiators in a complicated kidnapping case.

If that sounds like a premise that is not merely ridiculous but also somewhat uncomfortable (brainwashed young women being used as playthings by wealthy men, anyone?) rest assured that Whedon is a couple of steps ahead of you. As Entertainment Weekly's television critic Ken Tucker noted, Whedon's dramas have always been notable for their sly subtext (thus Buffy's vampires were a commentary on the agony of teenage romance and the perils of high school while Firefly's band of outlaws formed a very 21st-century family – heated, frequently pointless arguments and all).

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So it is that if Dollhouse's premise seems sexist it's precisely because Whedon intends it to seem so. This is Charlie's Angels by way of Eternal Sunshine of The Spotless Mind and the Bourne films. "What I wanted to do was talk about the idea of sex and what we expect of each other," Whedon told Salon.com's Heather Havrilesky when Dollhouse first aired in the US. "[It's about] power, love, how these things are all connected. We're positing the idea of, if people were in a position to give up their lives then how many of them would?"

It is precisely that question of free will, or rather of Echo's lack of it, which has so exercised critics in America. While the show has received some raves, notably from Havrilesky who said that Whedon was "combining intelligent layers of mystery with sly dialogue and a steady flow of action", there were just as many negative reviews, most notably that of The Washington Post's highly respected Tom Shales, who called the new show "a pretentious and risible jumble".

While Shales's view is overly harsh, it is certainly true that watching Dollhouse can be a frustrating experience, and one which is made more confusing by the sense that there are two very different stories battling to get out. The initial five episodes are stand-alone, relatively straightforward, procedurals with a slightly kitsch feel and little or no attempt to either understand Echo's predicament or delve deeper into why she has chosen to sign her life away – the opening episodes, in particular, with their broad plots and blunted dialogue, seem to serve more as a showcase for Dushku's acting ability than as a example of Whedon at his subtle best. But then, around episode six, something entirely different happens. The show finds its feet, we are treated to the beginnings of a complex mythology, ciphers become well-rounded characters and you find yourself genuinely caring about the people trapped in the mysterious Dollhouse and wondering whether they can escape from their increasingly disturbing predicament.

In a recent interview with the Chicago Tribune Whedon admitted that Dollhouse has undergone a number of growing pains. "Fox [the network who commissioned the show for the US] said, 'do the stand-alone episodes so that people can understand it, so that people can get into the mythology,' which I get," he said. "But because the process got a little twisted some of the stand-alone episodes didn't end up being as textured as I thought they could be."

And even though the new episodes are as involving and addictive as Whedon's best work, it is also clear that there are still problems. For a start Fox remains a network notoriously uncomfortable about taking a gamble on cult shows with low ratings, as their recent cancellation of The Sarah Connor Chronicles illustrated. And, while Dollhouse has done better than the Terminator reboot, it is also true that the ratings haven't been exactly set the world aflame. The most recent episode drew a disappointing 2.9 million viewers, and it's arguable that, as Dollhouse becomes more nuanced, allowing Whedon's strengths of characterisation and dialogue to come to the fore, so casual viewers searching for an undemanding hour of Friday-night television will become less interested.

Whedon, who remains philosophical about the realities of working in network television, has been here before. In contrast to some show-runners he is a notoriously slow starter ­– neither Buffy nor vampire drama Angel really hit their stride until their second seasons, while Firefly was just reaching its peak when was it was abruptly cancelled, 11 episodes into its run.

"I got to fly under the radar for eight years on networks so magical that they no longer exist," he admitted recently to the Chicago Tribune. "As soon as I came onto the radar and started playing in the grown-up world with Firefly and Dollhouse I started being treated the way every show-runner is treated. I did think, 'I've had a track record, so they'll get it'. But there's no such thing as a track record. You toil and you toil and you argue and argue and you tear your hair out and go nuts and eventually you either retire, go mad or become powerful enough to make your own show."

As to whether Dollhouse itself will survive, Whedon insists that the network remains supportive and understands what he is trying to achieve. "They're waiting to see what happens," he said recently at industry event, Paley Fest. "Fox has said that] the numbers are solid, the demographic is wonderful and the DVR [digital video recorder] ratings have been great, so right now I've gone from a sort of place of, 'you don't even care, nobody loves me to' to a place of God, I can't believe I'm saying this...hope.

"We might actually get the chance to do what we're dying to do, which is tell more of these stories with these crazy people. Ultimately it's about what happens in the next few weeks. I'm proud of the episodes we have coming up, we're going to go out with a bang... and hopefully we'll get to come back for season two."

'Dollhouse' starts on Sci-Fi on 19 May

JOSS WHEDON'S SEMINAL MOMENTS

Buffy The Vampire Slayer: 'Surprise' and 'Innocence'

The season-two episodes where the show really came into its own as Buffy finally slept with Angel, only to discover that loving a vampire has a terrible price. Probably the best metaphor for the over-the-top nature of teenage romance ever.

Buffy The Vampire Slayer: 'Once More With Feeling'

The musical episode. When Whedon announced that the seventh episode of Buffy's sixth season would be an all-singing, all-dancing extravaganza, even devoted fans worried. They shouldn't have. "Once More With Feeling" takes everything great about the show – the mythology, the humour and the detailed characterisation – and then ramps it up to 11.

Angel

The LA-set spin-off to Buffy was initially dismissed as the original's poor cousin but gradually developed into a darkly entertaining show in its own right. Among the standout episodes were season three's terrifying "Forgiving", in which Angel faces off against former friend Wesley in a bid to track down the vampire's lost son.

Firefly

With Buffy and Angel entering their final seasons, Whedon headed off to try something new at Fox. The result was this witty space-opera, which Whedon pitched as "nine people looking into the blackness of space and seeing nine different things". Prematurely cancelled midway through its first season, the show was rebooted as a successful movie, "Serenity".

Dr Horrible's Sing-Along Blog

Just when you thought that nothing Whedon would ever do could top "Once More With Feeling", along comes this 43-minute musical film about a super-villain in love. Originally aired on the internet during the writers' strike, "Dr Horrible" became a sensation, and went on to win seven Streamy awards (given for web television) including the audience choice for best web series.

Whedon appears on Veronica Mars

From the moment this cult show about a teenage detective aired Whedon heaped praise on it. His reward was a second-season cameo playing an overbearing car-rental employee alongside a contestant from "America's Next Top Model". To his credit Whedon kept a straight face throughout.