By Neil Smith Entertainment reporter, BBC News

Tim Roth (l) plays a hard-nosed journalist reporting on the disaster

More than 200,000 people were killed when an earthquake beneath the Indian ocean sent massive waves crashing ashore on 26 December 2004.

Filmed on location in Thailand, one of the countries worst affected by the disaster, Tsunami, The Aftermath follows a group of fictional characters whose lives are forever changed by the devastation wreaked on the holiday resorts of Phuket and Khao Lak.

Based on extensive research and interviews, the two-part film is written by Abi Morgan - best known for her award-winning dramas Murder and Sex Traffic.

"Obviously I didn't want to intrude on anyone's grief or plagiarise anyone's story," she says. "But we needed to do it as soon as possible to keep the memory alive."

'Deeply personal'

Director Bharat Nalluri, whose previous successes include Life on Mars and Spooks, admits the very word 'tsunami' evokes images of destruction and chaos akin to a Hollywood disaster movie.

"As soon as I started reading Abi's script, though, I realised it wasn't that at all," he says.

Okonedo and Ejiofor play parents looking for a missing child

"It was something far more profound and affecting - a subtle and deeply personal piece about how people respond to tragedy.

"The great power of drama is it allows us to follow very complex stories."

Of the many stories that interweave over the course of the three-hour programme, one that stands out is that of a young couple struggling to cope with the loss of their six-year-old daughter.

Actor Chiwetel Ejiofor, who plays the girl's distraught father, said he had some reservations about accepting the role.

"It's hard not to feel invasive somehow," he says. "But I think it was important to tell the story as quickly as possible.

"When I read the script, I realised there was so much I didn't know about the tsunami and what happened afterwards."

'Absolute integrity'

In a cast that includes Oscar nominees Tim Roth, Toni Collette and Sophie Okonedo, Britain's Gina McKee stands out as a widowed mother trying to arrange a flight home for her wounded son.

The Sunderland-born actress admits to having similar concerns to Ejiofor, but says Morgan did "a terrific job".

The cast also includes Toni Collette and Thai actor Samrit Machielsen

"I'm not sure how you time something like this," she tells the BBC News website. "How do you know when the time is right?

"But the film deals with the event in a mature and responsible way, and I knew that it was being done with absolute integrity."

In addition to the personal stories of those caught up in the catastrophe, Tsunami also looks at wider issues concerning the international response to the incident and the need to implement and improve early warning systems.

It also suggests that some hotel chains exploited the tragedy by building on land where fishing villages once stood.

"When you go to Thailand you see how it affected the people and how it's still not back to normal," explains actress Kate Ashfield, who plays a hotel chain representative in the BBC-HBO co-production.

"I hope the drama highlights what a beautiful country it is and demonstrates that we bear a global responsibility for these disasters," adds Abi Morgan.