TIFF: How Brie Larson Prepared for Her Role in Captivity Drama 'Room'

The 'Trainwrecked' star plays a young woman held captive with her son in a tiny room in Lenny Abrahamson's harrowing indie drama.

Room star Brie Larson on Monday said dredging up childhood memories of her parents' divorce helped her prepare for her star-turn in Lenny Abrahamson's harrowing one-room captivity drama.

"Sometimes you never fully understand why you're attracted to a project until you get deeper into it," Larson told the Room press conference at the Toronto Film Festival. The Canadian-Irish drama has Larson playing Joy, a young woman kidnapped and held in a tiny, windowless room for seven years with her son Jack, played by 8-year-old Jacob Tremblay.

To prepare for A24's adaptation of Emma Donoghue's unsettling novel, Larson said she went on a "silent retreat" where memories of living as a 7-year-old with her mother and younger sister in a tiny Los Angeles studio apartment flooded into her head.

"The bed came out of the wall. It was a room," she explained. The Trainwrecked star said one emotional image her mother stood out from happier memories of that time in her life.

"I remember waking up in the middle of the night to my mom with her hands over her mouth, trying to be quiet, and just sobbing uncontrollably, with convulsions and shaking," Larson recalled. Only years later did Larson learn her father had asked for a divorce, prompting a move to Los Angeles.

"That for me, was such a huge part of my life, and something so palpable for me to bring to this film,' she shared about her early life. Room is told from 5-year-old Jack's perspective, with his mother doing everything she can to create a complete and fulfilling life for her son.

But events eventually reach a breaking point and the young mother hatches a risky plan for escape. Room also stars Joan Allen as Joy's mother, William H. Macy as Joy's father and Tom McManus as her new stepfather.

Director Abrahamson praised Larson's performance in the drama during the Toronto presser. "Brie has this special quality as an actor. She can go to those dark and emotionally raw places, but she does it with such a simplicity and grace. There's no showboating," he said.

Room, which debuted in Telluride before shifting to Toronto, opens on Oct. 16 in a limited bow, before expanding nationwide on Nov. 6.