At first I thought the title was a made-up word. I had heard of placebos, of course, where the psychological state of the patient can literally will positive benefits from medicines that are not even medically there. I had never occurred to me that there would be an opposite – a fear of side-effects so palpable that one feels them whether real or not. That strikes me as a terrifying notion; no surprise, then, that the term ‘nocebo’ is headlining a horror film.

Christine (Eva Green) is a children’s fashion designer who has been struck down by an undiagnosed illness that causes physical pain, dizziness, and memory loss. Her condition places strain on her marriage to Felix (Mark Strong) and her relationship with her young daughter Bobs (Billie Gadsdon). With the arrival of a Filipino caregiver named Diana (Chai Fonacier), Christine life may finally be on the mend: but why has Diana arrived, and why can’t Christine remember hiring her?

Directed by Lorcan Finnegan (Vivarium), Nocebo is a stand-out supernatural thriller. It is an Irish-Filipino co-production, and takes enormous advantage of its multicultural set-up. The framework is immediately familiar, with a woman largely confined to a large house and experiencing some form of supernatural disturbance. It is a genre well played by Irish and British horror films alike. With the arrival of the eerily pleasant Diana, however, there is a shift to incorporate elements of Southeast Asian folk horror as well.

It could be a worrisome tightrope for a film to balance on, with a white director (and writer: Garret Shanley) taking advantage of another culture’s genre tropes. Thankfully the film does exceptional work to ensure this never becomes some vicarious act of post-colonial tourism. Diana is given an immense level of agency in the story, and time to flesh out her character. The supernatural elements are respectfully utilised, and Shanley’s screenplay goes well beyond avoiding colonial tendencies like Orientalism and actively works against them. It is not simply an effective thriller, it is smart as well.

Eva Green and Mark Strong are well-regarded actors with deserved reputations, and they perform very well here. Billie Gadsdon is well directed and effective as their daughter Roberta, nicknamed “Bobs”, which is good as the screenplay leans on her character as much as it does anybody else.

The real stand-out here is Chai Fonacier – already a successful actor and musician in the Philippines – who forms a three dimensional character with depth and levels one regularly fails to see in genre pictures. She is a complicated figure to play, as the film’s loyalty shifts back and forth around her. Is she the antagonist, or is she something else. Fonacier is absolutely superb.

This is a modestly budgeted film, but it does a very good job of getting its money up on the screen and in the sequences that really count. Some moments get visceral, and the sudden fashion in how they emerge adds energy and emotional power. Photography by Jakub Kijowski and Radek Ladczuk is superb, as is Jose Buencamino’s musical score. In these kinds of slow-burn, insidious horrors, the tone can mean everything – and Finnegan and his crew positively nail it. There has been a mini-renaissance in Irish screen horror in recent years, much like the one in Australia. It is brilliant to see, and Nocebo is an absolute highlight.