28 Weeks Later (18) Sequel to horror film about a deadly virus wiping out Britain, starring Robert Carlyle.

The follow-up to the hugely successful 28 Days Later, 28 Weeks Later picks up six months after the rage virus has annihilated the mainland Britain.

The US army declares that the war against infection has been won, and that the reconstruction of the country can begin.

As the first wave of refugees return, a family is reunited - but one of them unwittingly carries a terrible secret. The virus is not yet dead, and this time, it is more dangerous than ever.

"We were quite taken aback by the phenomenal success of the first film, particularly in America," recalls producer Andrew Macdonald.

"We saw an opportunity to make a second film that already had a built in audience. We thought it would be a great idea to try and satisfy that audience again. The hard bit was to try and find a story which would live up to the power and depth that Danny (Boyle, director) and Alex (Garland, writer) brought to the first film."

28 Days Later told the story of when the virus was first unleashed following a raid on a primate research facility by animal rights activists.

Transmittable in a single drop of blood, the virus locked those infected into a permanent state of murderous rage. Within 28 days, the country was overwhelmed and a handful of survivors desperately struggled to salvage a future.

"Alex came up with a lot of ideas and eventually we agreed upon a concept about what would happen to the UK after the disease had been eradicated and the quarantine was lifted," explains Macdonald.

"What would happen if there were only 500 people populating the UK? Who would be there to organise the survivors and refugees coming back from overseas, and what would happen to the Brits who survived? All those questions seemed interesting to us and it was out of them that the story evolved."

The challenge of the casting process was to find the central family, who needed to be a believable and realistic unit around which the extraordinary events of the story evolve.

To play Don, the father, the filmmakers were looking for someone who could not only carry the film with his performance but also be a real leader on the set to help the children with their roles.

Robert Carlyle, a fan of the first film, had his reservations about his role as Don: "I was kind of worried at first because the first film was very good, so I was hoping that it was going to live up to it. But then there were a couple of moments in the script, in which I thought, actually, this is brilliant".

Carlyle adds: "Don has been project manager on building sites and self-builds. During the original outbreak, his children were in Spain on holiday.

"He manages to survive the beginning of the first 28 days along with his wife, and they take shelter in a cottage in the country. But that does not last for too long before the infected come knocking. He manages to escape, leaving his wife to her fate."

Catherine McCormack, who plays the mother, Alice, admits she was not a fan of horror films but had seen 28 Days Later and loved it. "I thought it was really edgy and innovative and had a real energy to it. That alone made me more than interested.

"Although Alice does not have a big part, she is integral to the story," explains McCormack.

"My character's eyes have different coloured irises which the audience later finds out denotes a genetic immunity to the virus. The audience later sees that her son, Andy, has also inherited her unusual eye pigmentation.

"When her husband, Don leaves her behind in the cottage to the infected he assumes she has been killed, but in fact she survives. So she has a chance to get back at those who left her in the lurch."

Rose Byrne plays Scarlet, a military doctor stationed with the American army as they quarantine Britain.

"She is very assertive and smart, but she is also a bit of a renegade in terms of defying the army and the codes," explains Byrne.

"I really enjoyed this kind of genre film. I love horror. I remember begging my mum for me to rent out Nightmare On Elm Street when it came on to video when I was about 12. I have also always loved Halloween, Fright Night and Friday the 13th."