The “ultra, ultra low-budget” 18-day shoot itself proved arduous. Cramped in the derelict basement bathroom that was the film’s central location, Wan was constrained not just by the walls but by the tight budget and scheduling strictures.

“I was really bummed by the time post-production came around,” he confesses. “I felt like I didn’t really make the film that I promised myself I was going to make and I was ultimately going to blow my opportunity as a filmmaker.”

For the three main actors, the shoot was equally gruelling as they found themselves trapped on a single cold set for 12-hour stretches.

As the screenwriter, Whannell only had himself to blame. “Leigh could have written a movie like Clerks about two guys in a supermarket talking,” jokes Wan. "But instead it’s two guys in a dingy basement...”