Joy (Brie Larson) was kidnapped at the age of 17 and 2 years later gave birth to her son Jack (Jacob Tremblay) by her kidnapper Big Nick (Sean Bridgers) where we meet them as Jack celebrates his 5th birthday in the 10 X 10 room, a shed, the only place he has ever known, never going outside. What he knows of the world outside of the shed he has seen on the small TV set they have or been told to him by his mother.
The shed has a small sink, 2 chairs, a tub, a bed, a small table, a toaster oven and a closet where Jacob is put in by his mother every time Big Nick comes to rape her. The room is decorated with drawings by the boy and his imagination sees all the things as his friends and the world visible from the very small, very high skylight unimaginable though his mother teaches him to read and explains all the things he sees on the TV as being real.
We spend the first 50 minutes with mother and son, with short visits by their kidnapper to abuse her, in what could be a claustrophobic segment but we watch the mother use discipline with her son making him exercise, learn to read, follow oral hygiene, break eggs, learn how to cook and use his imagination. Without telling too much one of the most touching scenes for many reasons is when the pair make a cake for his 5th birthday.
The second half of the film deals with their escape--leave logic at the door as it is the only misfire by director Lenny Abrahamson--and what happens to the mother and son coming into the real world.
Based on her book and writing the screenplay Emma Donoghue does a good job holding our interest in both segments but I wish there had been about 5-15 minutes more regarding the relation between Joy, her mother (Joan Allen), her father (Willaim H. Macy) now divorced, and their reaction to getting their daughter back 7 years after she was kidnapped.
Allen does a excellent job, Macy is wasted in no more than a cameo though his reaction is important to his daughter's freedom. Bridgers, looking like your next door neighbor, is menacing in his lack of looking menacing while  Tom McCamus, as the new man in Allen's and now also in the Joy and Jacob's lives is underplayed.
Brie Larson is strong, weak, protective, questioning, as the mother who wonders whether she could have done better by her son after doing all she could while they were prisoners.
Jacob Tremblay is a revelation as 5 year old Jack whether it be using his imagination about the outside world or when he gets there dealing with it. There were a few times he was incomprehensible on the soundtrack where he does some key narration but just by looks and action he carries the scenes whether alone or dealing with the adults.
This sounds like it may be a depressing film and the theme certainly isn't a light one but Jacob Tremblay, at 9 years old, lifts the film up with his acting, his open face and looking at the world with wonder, showing that children can handle life better than most adults.
“ROOM”   TRAILER
 
https://www.youtube.com/watch?v=E_Ci-pAL4eE