If there's one phrase that leads film fans to roll their eyes, it's "based on a true story". The phrase has become a byword for filmmakers' embellishment of events, manipulating or corrupting real-life accounts for the sake of generic convention. We're all familiar with the complaints about movie logic, Hollywood's tendency to romanticise or dumb down, and the on-going debate about how far cinema should go in accurately depicting human interactions. With all this in mind, you might consider giving The Impossible a very wide berth. Not only is it "based on a true story", but it deals with natural disasters - a sensitive subject at the best of times. The Boxing Day tsunami still feels relatively recent, and there are any number of traps into which a director could fall in attempting to address it. But while it does still raise all these familiar questions, The Impossible is still a very good film, delivering more than its share of emotional punch. One of the challenges of doing any kind of big set-piece lies in balancing the many different kinds of effects. Since Total Recall and Terminator 2 kick-started the CG revolution, there has been a growing trend towards CG over organic effects, both as an internal economy and to avoid putting actors and stunt-people in needless danger. But effects are only as good as the people directing them, and in this kind of story, you can't afford to have water that looks like it escaped from Die Another Day. Fortunately, The Impossible is in good hands in this regard. Juan Antonio Bayona learnt his craft under the patronage of Guillermo del Toro, who produced Bayona's brilliant debut The Orphanage. Both directors understand what different kinds of effects can achieve, and how important it is to physicalize a character or threat wherever possible. While there is a fair amount of CGI involved, the vast majority of the tsunami scenes were filmed using real water, with the actors being thrown around in the same kind of tidal tanks that Ang Lee employed in Life of Pi. It's not just the big-scale effects that impress, however. Equally good are the prosthetics and make-up, which cause us to refocus our attention on the characters and conspire to make the whole thing feel horribly real. For a 12 certificate, the film is incredibly brutal, with the only punches pulled being in the relatively fast editing whenever blood is spilled. Certainly you'll struggle not to recoil in horror at the sight of Naomi Watts' badly-damaged leg. This leads us onto the second big success of The Impossible, namely getting us invested in the characters. As before, it's very easy to roll your eyes and pigeonhole the characters according to the familiar ciphers and conventions of stories about the triumph of the human spirit. But once again Bayona confounds us, assisted in this regard by The Orphanage screenwriter Sergio G. Sánchez. While there are issues with the narrative itself, the central characters are well-drawn and feel naturalistic in both their actions and their reactions to what is happening. If nothing else, The Impossible confirms Bayona as a great director of child actors. He has a gift of getting great performances from very young talents, which is magnified by the skill he has at showing this world from a child's point of view. The film is at its best when we see all the devastation and emotional anguish in terms of the children caught up in it, whether it's Simon and Thomas quarrelling on the bus, or Lucas looking after his mother and wandering around the hospital with the list of names. Like The Orphanage before it, The Impossible centres round parents and children searching for each other. In both cases the adults take up a lot of the screen time but are not the driving force - Naomi Watts has as little control as Belén Rueda over the fate of her child or the environment in which she finds herself. Bayona's touch is such that it lends the production an innocence which amplifies the drama and lessens the impression that we are being manipulated. The performances in The Impossible cement Bayona's efforts and are often the key to elevating the story above convention. Tom Holland is outstanding as Lucas; like all the best child or teenage actors, he is wise beyond his years but avoids coming across as overly mannered. His reactions are naturalistic and believable, and he handles the darker material very capably. Naomi Watts continues to put herself through the mill as an actress, turning out another gripping, no-holes-barred performance. For once Ewan McGregor is a little flat, being generally convincing but not managing to hold his own in his sections of the story. As a character piece, The Impossible is a well-crafted film that deserves plaudits for the way in which its story has been staged, both technically and narratively. But upon closer scrutiny, there are a couple of narrative shortcomings which prevent the film from ascertaining greatness. Ultimately its emotional depth is more than enough to see us through, and while we're watching the film these shortcomings don't interfere too greatly. Instead they are niggling little questions which emerge in the aftermath, and which take just a little bit of the shine off what is otherwise a very fine effort. The story of the film is relatively simple but well-told in terms of its character arcs and development. The script, however, isn't always strong on dialogue, with the endless shouting of names drifting a little close to Titanic and a few occasions where supporting characters monologue about their place in the universe. There are also some big melodramatic contrivances, such as the manner of the family's reunion or the resolution of Daniel's subplot. If these events did happen exact as shown, they are clumsily conveyed; if they didn't, they have no real business in being there. The much bigger criticism, which seems to have dogged the film, is that of alleged "whitewashing". There are, in fact, two separate accusations. The first concerns the nationality of the family, which are changed from Spanish to British (at least as far as accents are concerned) - the argument being that this was done to appeal to American audiences who might not read subtitles (so the stereotype goes). The second concerns the Thai presence in the film, with the attention focussing on the plight of Western tourists and not the pain and devastation of Thai nationals, who did not often have access to the support or resources enjoyed by the main characters. It is certainly true that The Impossible focusses on privileged white people, but it also doesn't make any massive attempt to say that their experience is typical. It is possible for an extraordinary story to convey universal themes, and vice versa. Because of this, the Thai characters are marginalised, and it is fair to assume that a film made from their viewpoint would have been more brutal still. You could even argue that the film has the problem as Shame, depicting something truly horrific while ultimately feeling a little too choreographed to truly win us over. Ultimately, however, The Impossible has such a strong emotional pull that we are invested in the characters regardless of their race or status. These criticisms emerge during the moments of narrative contrivance or slack scripting, but for the most part the film is not dogged by these problems. Bayona's storytelling is efficient and he balances the two sides of the family reasonably well. It may not be the deepest disaster film ever, but it is one of the most emotionally weighty. The Impossible is a really good film whose myriad successes ultimately overshadow its shortcomings. It tackles a very difficult subject matter with sensitivity and aplomb, offering us a host of good characters and great performances in which we can really invest. It's not without its problems, narrative or symbolic, but it's still a gripping and visceral drama that really deserves to be seen.