This Spanish movie, scripted by Sergio G Sánchez and directed by JA Bayona, the team responsible for the accomplished Spanish horror movie The Orphanage, is a carefully researched account of one family's experience of the tsunami that struck south-west Asia on Boxing Day 2004, taking the lives of more than 250,000 people and causing untold destruction. Henry Bennett (Ewan McGregor), a British businessman working in Japan, his wife Maria (Naomi Watts), a doctor temporarily retired from practice, and their three preteen sons are spending their Christmas vacation at a luxury Thai resort. They're having an idyllic time playing with their presents and snorkelling in the crystalline water, but there's something amiss. The kids are fractious, a page keeps blowing out of the thin book Maria is reading, and Henry gets a text message that he's about to lose his job. Then suddenly their world is turned upside down as the tsunami strikes while they sit around the pool.

There follows a spectacular, visceral re-creation of the gigantic wave and its horrendous consequences that separate the Bennetts, carrying the seriously injured Maria inland along with her eldest son, Lucas (Tom Holland), and leaving Henry near to the shore with the young boys, Thomas and Simon. Neither party knows the others are alive, and the pain of separation is palpable. Lucas first falters then rises to the occasion, escorting his mother to hospital and then taking on the job of uniting parents with their lost children. Henry briefly loses his nerve but recovers, putting his small sons into safe hands to search for their mother. One boy, already fascinated by astronomy, has a moving encounter with Geraldine Chaplin (ungallantly billed as Elderly Woman) about cosmic matters.

The film is well acted, the makeup convincing, the turbulent mise en scène impeccable. We are immersed in the immediate experience of the tsunami, but its larger context and its consequences are ignored. The film carries a declaration that this is the true story of a representative family. In fact the real family were Spanish, the Alvarez Belóns, whose story has been transformed into an English-speaking one, designed for worldwide acceptance. The final credits are prefaced by a photo of the Alvarez Belóns, smiling for the camera, dark-haired and good-looking, and physically not much like the fair-haired Bennetts.