The film, based on Emma Donoghue's 2010 novel of the same name, follows a 5-year-old boy who has been held captive with his mother in a small room, reported Entertainment Weekly.
Brie Larson, who most recently appeared in "Trainwreck" plays the mother, and "The Smurfs 2" star Jacob Tremblay will play her son.
The drama has been selected to be shown in the Special Presentations section of the 2015 Toronto International Film Festival to be held in September.
"Room" also stars Joan Allen, Sean Bridgers and William H Macy.