Director Joss Whedon has said he made new film Serenity partly because he wanted to see the return of the "gritty" side of science fiction.
Whedon's original Firefly series was cancelled after just 11 shows
Whedon, best known as the creator of Buffy The Vampire Slayer, based Serenity on his own short-lived TV series Firefly.
In it, a crew of rebels and smugglers - the losers in a war against a brutal military dictatorship known as the Alliance - are pursued after giving a lift to two mysterious strangers, one of whom is a teenage psychic.
"There's something in science fiction, which I love very much, that I've missed of late - which is a sort of grittiness, the reality of what it must be like to be up in a small community or a small ship," Whedon told the BBC.
"So I had a perfectly disparate set of elements - I had people who were actual size in a story that was larger than life, and I think when you put those two elements together you get the most exciting kind of film-making."
Touch of Solo
Whedon said that much of Serenity has elements of a Western, in terms of the element of life on the edge, where people exist remotely in areas where laws are often non-existent.
He admitted that the term "science fiction/Western" made people "cringe", but he said that the genres were interesting because they reflected a way of life that was ever more distant in an inter-connected world.
"They think it's going to be big hats, and it's going to be hokey. The fact of the matter is that I think the two are intrinsically related, because it's the final frontier - and what's exciting about frontier life is the physicality of it.
"That's something that we're losing in the internet age.
"So to me, the Western and science fiction belong together."
Serenity features a number of powerful female characters
Unusually for a film of this type, the commander of the ship, Mal Reynolds - played by Nathan Fillon - is not an obvious hero, although the story is about him.
Whedon admitted there was more than a touch of the Star Wars character Han Solo in Mal.
"I've seen Star Wars more times than I care to count, and Han Solo is an enormous influence on Mal," he said.
"The idea of the way Han Solo lived was really one of the biggest inspirations for the show - but it was the idea of, 'what if he just lived that way, and never met Luke Skywalker and never heard about the Force - what if he just had to make a living?'
"Then, when he's finally presented with a truly epic story - which is what happens in the film - it's not a happy story."
Through Mal's powerful lieutenant Zoe, Serenity also continues the theme of strong female characters - something that is consistent throughout Whedon's work, dating back to his first job as a scriptwriter on comedy series Rosanne.
"Zoe is possibly more powerful than Mal, because her moral compass didn't get knocked out of whack when she lost the war," he explained.
"She's somebody who has managed to make a very decent normal life. She has a strict sense of morality, and absolutely can command both the ship and the crew."
Whedon is now in the midst of tackling another strong female character, as he is directing the feature film version of Wonder Woman.
"I hadn't intended to make the movie until I started thinking about what that character was, why she was an icon," he said.
"What was fascinating about her was that in a way she'd become an icon without the benefit of some of the great storytelling that had been done in some of the old and more recent Superman, Batman and Spidermans.
"She's a goddess, and she will not be denied. I tried to deny her and failed."