TORONTO – Trapped inside the tiny set of “Green Room,” seven actors were slowly losing their minds as they stared at the carnage before them.

One cast member was writhing on the floor in agony while the others paced the space, which doubled as the cramped backstage of a neo-Nazi club.

Blood was pouring everywhere and the tension was becoming so thick the film’s script supervisor broke down in tears.

“That world is so potent,” says actor Anton Yelchin, reflecting on the experience of making the gritty thriller with a small film crew.

“There’s 15 people in an enclosed room with smoke pumped into it. It’s very emotionally draining.”

Yelchin — known for his role as Chekov in the latest “Star Trek” movies — was at the centre of the action playing a member of a punk band that unexpectedly witnesses a grisly murder.

Boxed into a music venue’s green room, the group begins a desperate fight for their lives.

Patrick Stewart, a fellow “Star Trek” alum and leader of the captors, says he could feel the intensity inside the room — even though his role is played outside, separate from most of the violence.

“There are a lot of startling moments. It’s quite shocking and not for the squeamish,” he says.

Stewart’s calm and collected villain elevates the uncertainty that charges through the film’s pulse-pounding sequences, which play in near real-time.

Director Jeremy Saulnier says the challenge of “Green Room” was making each moment seem like an act of desperation.

“The pitbulls, the stunts, the shotguns … that was the easy part,” Saulnier says.

“The hardest part was keeping this movie hyper intense.”

Saulnier says he grappled with his own career direction in the aftermath of his previous film “Blue Ruin,” which caught the attention of Hollywood executives with its explosive moments of violence ripping through the suspense.

They wanted the indie filmmaker to helm their own big-budget projects with a similar bent.

“I was at a crossroads,” he says. “All of the sudden I had opportunities I’d never dreamt of.”

But instead of taking the bait, as he puts it, Saulnier tackled a challenging project that appealed to him personally.

“Green Room” is based on a script he wrote and pays homage to his roots as a teenage filmmaker who raced around with his friends shooting footage on a camcorder for the pure love of it.

“The movies we made were like goofy zombie comedies or violent cop movies,” he said.

“Something about it felt so pure and I wanted to celebrate that and also make a film that just wouldn’t be about shocks and good times, but also a legitimate emotional journey.”

“Green Room” opens Friday in Calgary, Edmonton, Halifax, Hamilton, London, Ont., Ottawa, Toronto, Vancouver, Victoria and Winnipeg.

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