Christmas Eve 2004. The Japan residing Brits, the Bennetts - husband and wife Henry and Maria, and their three sons Lucas, Thomas and Simon - have just arrived at the Orchid Beach Resort in Khao Lak, Thailand, for their Christmas vacation. They are all at the resort's pool area - Henry with the two youngest in the pool, while Maria and Lucas are off doing other things on their own - when, without warning, a massive tsunami hits. In the tsunami's aftermath which results in a landscape full of carnage and destruction, the surviving family members, some with serious injuries, are separated from each other. The first priority for each is to find at least one other family member so that he/she is not alone in dealing with the uncertainty of the situation. Once he/she is able to do so, they have to decide if finding the other family members, not knowing if they are dead or alive, should still remain the only priority, especially as some things become better known and as other things are still unknown, such as if another tsunami will hit which makes heading to higher ground a sound move for one's own safety. Along the way, each person will have to decide whether to help others, and conversely if others are willing to help them, most of who are facing the same situation of being injured and requiring medical assistance and/or are looking for missing loved ones, not knowing if they are dead or alive.