Dog Soldiers, Marshall’s first feature, was an action-horror hybrid about a squad of soldiers fending off a pack of werewolves during a training exercise in the Scottish Highlands. Getting it written, financed and made was a six-year struggle, but the film launched Marshall’s career. When it came to following it up, Marshall recalls—despite its violence and gore—Dog Soldiers struck some critics as too tongue-in-cheek; he was eager to make his next feature “as scary and dark as possible.”
Still exploring camaraderie under pressure, the filmmaker inverted Dog Soldiers’ character dynamics by depicting a group falling apart and turning against each other in response to an external threat. Originally, the cast was mixed-gender, but Marshall’s business partner highlighted how few horror films featured all-female casts, so they made the characters women. “In researching worlds of caving, climbing and extreme sports, I was finding as many women as men, so it felt perfectly authentic,” the director recalls.
Casting was everything, and Marshall took his time in selecting lesser-known actresses. It would be a physically arduous seven-week shoot, which meant he required strong actors willing to face their own fears—of heights, darkness and especially claustrophobia. Before filming, “we did a lot of climbing with the actors,” he adds. “All of us went on a full caving expedition, abseiling down waterfalls underground and crawling into tight spaces. It was astonishing.”
Before casting Macdonald as Shauna, “we auditioned the hell out of her,” he continues. “Once she came on board, she kept me on my toes with a constant stream of questions about where the character was going. Shauna is the emotional core of the story. We watch her go through so many changes, from sadness to fear to this rebirth through a baptism of blood, where her primal inner self comes out. She transforms into a fierce survivor-mother who’s killing everything in sight.”
