Twenty-four year old Joy (Brie Larson) lives with her five year old son Jack (Jacob Tremblay) in a small shed she dubs "Room." Unknown to Jack, Joy has spent seven years as the hostage of Old Nick (Sean Bridgers), who locks periodically provides food, medicine and supplies, while assaulting Joy. Joy engineers Jack's escape; her son's fascinated by the real world, while baffled by its contradictions. When Joy joins him, the situation grows worse, as she's unable to reconnect.
Room's most interesting in the opening hour, exploring the protagonists' limited universe. Jack interacts with bathroom fixtures and considers television magic. Joy's tales of a life outside are half-believed myths, as real as Santa Claus. She struggles to make life fun and meaningful for her son, who thankfully has no other reference point. Jack allows Joy, living a hellish nightmare, to retain her sanity; motherhood gives her meaning and motivation.
Director Lenny Abrahamson tackles Donoghue's story with restraint, playing up the cramped living space, underscored by quiet horror as reality bleeds through. Jack witnesses Old Nick assaulting his mother and realizes he's not so benevolent; Joy arranges an elaborate ruse to rescue her son. When Jack finally sees the outdoors, blue sky and leafy trees whooshing past, it's a magical release for him, and the audience too.
Room effectively climaxes then, which is a shame; there's nearly an hour left. Joy and Jack become media celebrities and bicker with Joy's disbelieving parents (Joan Allen and William H. Macy), forced to confront a tragedy they'd put behind them. Joy's abrasiveness and isolation leads her to despair; Jack can't understand why the outside world has rules, routines and conflicts. Fortunately, Jack connects with his grandparents, befriends a dog and makes a friend, providing some hope.
Brie Larson performs perfectly; her Oscar's well-deserved. Usually a comedic actress, Larson plays Joy's disconnect and quiet desperation, driven solely by maternal affection. Jacob Tremblay's restrained precociousness makes a cute counterpoint; Jack's the rare movie kid who's endearing rather than annoying. Joan Allen and William H. Macy effectively sketch Joy's parents, while Sean Bridgers is merely a menacing presence. Tom McCamus, as Joy's stepfather, is a likeable bit player.
Room isn't entirely satisfying for the same reason as Cast Away. It's fascinating watching Tom Hanks adjust to life on an island, less so watching him return to civilization. What should be a coda takes up nearly half the film. Still, it engages viewers in a bracing, original way that's undeniable.