It’s hard to pin down what kind of film The Block Island Sound is, but that’s actually a large part of its appeal.

The film hails from siblings Kevin & Matthew McManus, who were responsible for Netflix’s short-lived two season wonder American Vandal. Anyone familiar with that surprisingly smart and complex series won’t be surprised to discover that this latest project has the same kind of genre-defying sensibilities.

The Block Island Sound opens on Tom (Neville Archambault), an older fisherman who has been experiencing hallucinations and blackouts. Adult son Harry (Chris Sheffield) is concerned about his late-night disappearances, though Harry bristles at the suggestion that he’s not doing enough for his father when sister Audry (Michaela McManus) arrives on the island to investigate a weird environmental calamity. It seems that 9-10 tons of fish have washed up dead on the beach for no apparent reason, so Audry and her EPA co-worker Paul (Ryan O’Flanagan), as well as her pre-teen daughter Emily (Matilda Lawler), arrive to investigate.

Because The Block Island Sound opens on Tom mysteriously waking up in his boat on the water and Audry’s entry point into the narrative revolves around the dead fish, there’s every expectation that this is a new entry in the thriving aquatic horror subgenre. And yet, after Tom tragically dies and Harry succumbs to anger and alcohol abuse, the film takes on a completely different, hallucinatory vibe. Suddenly Harry’s drinking buddy Dale’s (Jim Cummings) ominous warnings of X-Files-like conspiracy theories take hold. And this is before Harry’s descent into paranoia tilts the film towards possession territory.

This revolving mix of subgenres would normally be a warning to audiences that the filmmakers don’t have a good handle on the film, but that’s clearly not the case. The clues to unpacking the narrative are present for those who pay attention, but the reality is that the McManus brothers are less interested in the mystery of what is happening than exploring Harry’s isolation and the friction within the family unit.

The heart of the film is actually the adult sibling relationship between Harry and Audry. She left the island to pursue her career and Harry was left to care for their ailing father in the wake of their mother’s death. There’s lingering resentment and conflict about how often she returns and the sense that he’s wasting his life. Intriguingly, neither of them is entirely wrong: Audry is something of a workaholic and a forgetful mother, but she’s deeply empathetic. Harry, meanwhile, with his rage and substance abuse issues, is the black sheep of the family, but he’s stubborn and suffers no fools. Their affection for and simultaneous wariness of each other feels authentic and lived-in. Just when it seems the film has them figured out a third sibling – bitchy type A Jen (Heidi Neidermeyer) – shows up to take charge of Tom’s funeral and throw things into further disarray.

As the film progresses and Harry becomes more unmoored from reality, it is his bond to Audry (and niece Emily) that keeps the narrative grounded and the stakes high. There’s rarely a dull moment, even when the McManus brothers focus on the potentially banal struggle to keep the family from falling apart in the face of supernatural elements. That this works at all is a testament to Sheffield’s brazen performance, who is completely captivating as Harry.

The other strength of The Block Island Sound are the visual techniques that the writer/director brothers use to capture Harry’s blackouts, time-ellipses and the final revelation of what is actually happening in the film.

Cleverly the McManus brothers stage not one, but two big reveals. The first time, the visual is so confounding that it barely registers before it’s done. This crafty introduction, however, anticipates a similar longer sequence that acts as the film’s climax, so that when it occurs again the audience understands just how dangerous the threat is. These are dazzling sequences that work because the McManus brothers understand what makes for a compelling visual, but also because their script has devoted the appropriate time and energy to building up the relationships so that the audience cares about the outcome.

Is it aquatic horror? Is it paranormal? Is it possession? Is it a government conspiracy? It may just be all of the above. Regardless of how the film winds up being categorized, by actively seeking to confront and confound genre expectations, The Block Island Sound is a daring horror mish-mash that is well worth seeking out.

The Block Island Sound arrived on Netflix March 11, 2021.

Editor’s Note: This Fantasia review was originally published on August 28, 2020.