TORONTO — “Doesn’t this look like where people come to get fired?”

Jennifer Lawrence was in a bland hotel conference room here, waiting for Darren Aronofsky, the writer-director of her new drama, “Mother!” It was a few hours before the film’s premiere at the Toronto International Film Festival. Mr. Aronofsky, her boyfriend, was running late.

“Where is he? I’ll call him,” she said and spoke into her phone: “Call ‘the Dark Lord.’ ”

She was kidding (probably), and just as typically unfiltered about the experience of making “Mother!”

“I really freaked out before this one,” she said. “I thought I’d been miscast.” Her starring role, as the unnamed “mother,” an earthy wife who doesn’t even leave the house, was a departure from the flinty, adventurous heroines that she is known for. “I’ve never felt so insecure,” she said.

What changed?

“Nothing,” Ms. Lawrence said jokingly. “We wrapped the movie, and I’ve been sweating bullets ever since.”