Rating: Where do they find these kids? No, seriously - how is Hollywood suddenly finding actors with ages in the single digits yet a maturity (in both acting and elsewhere) at a match, if not greater, than their adult peers? Aren't child actors meant to be cute, but understandably not quite able to deliver on some more complex emotions (which only makes them more charming)? Just as Beasts Of No Nation explodes onto Netflix led by a powerhouse turn by Abraham Attah as a child soldier, Room brings us Jacob Temblay (previously of Smurfs 2) as a five-year-old raised in confinement gaining a greater perspective on his little world. These arent the kids of yesteryear, but nuanced performers working with directors who know how to get the best out of their young stars. And Tremblay doesn't just deliver a subtle performance that unfolds over the course of Room; he's the main character of the whole thing. This tale of a kidnapped woman raising her conceived-in-captivity son is told entirely from the perspective of his character, Jack. It's through him we're first introduced to Room (in one of many sly examples of Jack's state of cognitive development there's no definite article) and, while as a viewer you bring all sort of context about the implications of his situation into the cinema, to our eye into the world this is all normal. That requires a complex representation of mental growth, and although a lot of it does come from the script (like Gone Girl adapted by the best-selling book's author), the young actor is totally convincing. I can't get over how impressive he is - Tremblay is nine as the film arrives with serious awards buzz, and was only eight while shooting. To put that in perspective, the first new Star Wars movie released in his lifetime is The Force Awakens. If his performance would be best described as surprising, Brie Larson's is more greatly satisfying. Shes an actress whos always been capable of great things, but never received that much notice; she excels at playing characters with wry, quiet intelligence, the exact sort that never get the chatter over more vocal co-stars. That's all about to change now as she runs the full gamut in a role that sees her as both victim and carer, broken and strong, yet through it all just a regular person. It's a balancing act that's heartbreaking to watch; "Ma" could easily be any one of her earlier characters thrust into this horrible situation, making the whole ordeal that bit more real (and reprehensible). Room is a film powered by emotion - particularly the bond between mother and child (even in the face of grizzly origins) - and driven by this pair of performances. To that end, Lenny Abrahamson has done a great job getting Larson and Tremblay to work harmoniously together, building a real bond between the stars that makes their relationship utterly believable, even if from a filmmaking standpoint there are a handful of directorial choices - heavy close-ups early on and a slight deviation from the established point-of-view in a key sequence - that mean some of the brilliance is slightly muted. And now's where things get tricky. What follows could be classed as spoiler talk, but it's nothing that isn't already in the marketing. Still, in the interest of fairness, if you haven't seen the film and don't want to know later events, I'd recommend you stop reading now (or skip to the very last paragraph). I went into the film expecting a lengthy exploration of Ma and Jack's imprisonment, with themes of paternal love accompanied with strong representations of cabin fever and Stockholm syndrome, but in actuality the time in Room is just the first half (and those psychological responses completely absent). That's right - Jack and Ma escape after about an hour, with the latter part of the film dealing with their adjustment/readjustment to the world outside the shed. It's a great idea, allowing for us to see the full impact of the kidnapping and the difficultly of moving on from such an ordeal. Sadly, the latest trailer has pretty much ruined any surprise this plot twist may have had - after initial marketing focusing on the time in Room itself, with the vague hint of escape in the third act, this ad breaks down exactly how Jack frees his mother and spends an inordinate amount of time on the pair adjusting to life in the real world. While knowing this wouldn't have affected my opinion of the film (I'm merely bringing up this element in an advisory capacity), it feels like a misjudged trick - part of the brilliance of the film's opening is that the spectre of hope is a far off for you as it is for Ma. Beyond that, though, I can't help but think the marketing department have shot themselves in the foot. Based on its Toronto success (it received the People's Choice Award, a prize previously won by Slumdog Millionaire, The King's Speech and 12 Years A Slave) Room has some serious Oscar credentials, but to capitalise on that it needs to thrive, or at least be looked upon kindly by the public. A movie being described as "all in the trailer" is one of the most damning audience criticisms there is, and could immediately nix that. But let's hope not. For all its minor faults, Room is a smart, emotional movie that forces you to bring your own moral questions to an unimaginable subject. I wouldn't say it's Best Picture worthy, but I'll be mighty pissed off if it doesn't get some acting noms; #LarsonForActress (and heck, #TremblayForSupporting) begin now. Seen as part of the London Film Festival 2015.Room is in US cinemas now and UK cinemas from 15th January 2016.