Confronted by the tricky question of how soon it becomes morally acceptable to mine real life tragedy for television drama, the creators of “Tsunami: the Aftermath” wisely settled on a sensitive, low-key approach — what you might call “respectful entertainment.” Not quite two years have passed since the Asian tsunami wiped out close to 300,000 lives in the blink of an oceanic eye, and the tone of this two-part HBOBBC production, which makes its premiere on HBO on Sunday, is mournful and muted. Yet, thanks to an intelligent script and an excellent cast, it is rarely less than engaging and often moving.

Different viewers will come away with different things, but for me the most lasting image is likely to be the anguished face of a man looking for his daughter. The face belongs to Ian Carter (Chiwetel Ejiofor), a black Englishman who, along with his wife, Susie (Sophie Okonedo), and 6-year-old daughter Martha, has come to the Thai resort and fishing village of Khao Lak for a quiet family vacation. Ian is alone with his daughter when the wave hits the morning after Christmas Day. He can’t hold onto her, but as the water surges past them she’s holding onto a tree and he’s urging her to keep holding onto it until something hits him in the head and he loses consciousness.

Miraculously, or unrealistically, Ian survives with nary a scratch. Hours later he is pulled from under a pile of palm fronds by Than (Samrit Machielsen), a placid Thai waiter at the hotel Ian and his family were staying in. By now the hotel is gone. So too are Ian’s wife and daughter, for whom he immediately starts hollering. “I have to find my family,” he says for the first of many times. But he also gazes in stunned awe at the mind-boggling scenes of wreckage around him.”What was that?” he asks. “I don’t even know what it was.”

This is the first enunciation of a paradoxical theme that will reverberate among the British tourists we follow through much of the film’s first half: The tsunami was not just an unusual act of nature, it was an unnatural one. Much later, during an angry meeting convened between the British Embassy and stranded British tourists, Ian interrupts a speech byTony (Hugh Bonneville), the ineffectual British Embassy offocial who’s saying something about stretched resources, the immense scale of such a natural disaster, etc. “There’s nothing natural about any of this,” Ian calls out angrily.”I want my daughter back.I want her here, and I want her now.” Contrast that with the stoical attitude of his Thai savior, Than, when Ian asks him why he shows so little anger. (Than has not only lost his family, he’s lost his village and livelihood too.) “Not what I want. How it is,” Than replies.

Ian is eventually reunited with his wife, but their daughter remains missing. The immediate strain this puts on their marriage, and on his wife’s sanity, is rendered with chilling realism and is the best part of the film. In the meantime, Sue (Gina McKee), an English woman from the hotel who was widowed overnight, helplessly wanders the corridor of a local hospital with her youngest son in tow while her older son lies in bed, near death. She pleads with Tony to have him flown to Britain for medical treatment, but there aren’t enough flights and, being cripplingly polite, she’s almost as feeble at pleading as he is at leading. Either that, or her son isn’t considered important enough to qualify for a seat on a plane — it’s hard to tell. But this film, which is almost entirely the work of Britons, from the director on down (the only trace of anything American about it is limited to the label “HBO”), is extremely critical of the British relief effort.

Chief among the critics are Nick, a swashbuckling journalist (shades, stubble, cigarettes, motorbike) who Tim Roth cleverly manages to avoid turning into a complete cliché, and a perennially cheerful Australian, Kathy (Toni Collette), a Christian charity worker who comes to the disturbing discovery that she is happiest — meaning most usefully herself — amid chaos and tragedy. Her primary job, aside from helping the victims, seems to be to try and prod the overwhelmed British ambassador into a semblance of action. She has some disparaging things to say about Nongovernmental Organizations, but the details are left vague (“meetings about meetings”). The filmmakers evidently feel safer chastising their own government than taking on representatives of the international community.

For Nick, who seems to be the only journalist in the place (he’s accompanied by an Asian photographer), the stories come thick and fast: For sanitary and religious reasons, Thai monks have started burning corpses, some of them foreign, before they have been identified; developers are demolishing the remains of the locals’ beachside homes so that no one will be able to reclaim their property; a Thai scientist warned the government years earlier about the danger of a tsunami, but his findings were shunned. Nick also reports on a young English woman (Kate Ashfield) who represents a major international hotel chain. She originally came to Thailand as a backpacker, fell in love with the place, learned about it, got a job in the tourism industry, and is now precariously close to being cast as a villain. It’s a minor role, but her story resonates.

As drama, “Tsunami: the Aftermath” is just a little bit too scrupulously unsensational for its own good: an anti-disaster disaster movie. Only in the relationship between Ian and Susie, and their harrowing search for their daughter, do emotions cut to the bone. And when Susie discovers an unclaimed girl who looks like Martha but isn’t and temporarily “adopts” her anyway, and for a while seems almost to convince herself that she is Martha, you can feel the “news” being left behind as the film starts to soar on the wings of invention.

Nonetheless, as a form of dramatized news, this is a touching and educational film in which all sides, even the rapacious corporations taking possession of the beachfronts, ultimately get their say. One can’t imagine it drawing crowds at the cinemaplex — “I want more wave, dude” — but in the living room, in front of the all-purpose television set, it should be a different story.

bbernhard@nysun.com