The film is set in 1976, just after the heyday of the giallo. Gilderoy, played by Toby Jones, travels to Italy to oversee the post-production audio of a Susperia-esque film (which in no way resembles a giallo, despite what all the reviews would tell you) called The Equestrian Vortex. We follow Gilderoy as he becomes increasingly isolated from, and then subsumed into, the unfamiliar environment and petty backstage squabbling.
The foreign fish-out-of-water aspect of traditional gialli is alive and well here, and it's hard not the think of Umberto Lenzi's recent interviews whenever Santini, the egotistical director of The Equestrian Vortex, is on screen. And the sound recording process, and equipment, is fetishised throughout, with regular close-ups of a black-gloved finger operating the playback machine. It's not exactly a faithful reconstruction of the working conditions of the era, if the interviews with participants in Italian post-production are anything to go by. The idea of importing a sound specialist would have been seen as a ludicrous extravagance, and the whole process was usually exported to a separate facility, with minimal involvement from the producers. And, if an expert was imported, he wouldn't have been kept around for long enough to be driven mad by the process (though the fact that his flight allegedly didn't exist hints that he may not actually have been imported).
In his commentary for the film, Peter Strickland suggests that there are hidden, but accessible , clues scattered throughout the film which point towards a 'correct' interpretation of the events depicted. He does acknowledge, however, that alternate readings of the film are just as valid as his own. This is a counterpoint to the giallo investigation of a film such as, say, Deep Red, where the interpretation of sounds and images is at the core of the plot, with everything hinging on the correct interpretation. Here, rather than a pursuit of truth, the focus is on a pursuit of meaning, with no one true answer.
The film ultimately is a mixture of art film and psychological thriller (going easy on the thriller aspect), and the last twenty minutes will probably leave some viewers scratching their heads and contemplating donning black gloves to murder Peter Strickland, but as someone who's ploughed the lonely post-production furrow (albeit in the comfort of my own living room), I could identify all-too-readily with the encroaching madness which threatens to overwhelm a lengthy post-production process. And, as with Gilderoy at the end of this film (KIND OF SPOILER), when the lights go out on the life of a filmmaker, we're all subsumed by our art, if, indeed, our art survives at all.