Almost a week after catching its New England Premiere, I find myself struggling to put down the right words to describe Ricky Bates Jr’s third film. While it was the standout among a number or worthy contenders at last weekend’s Boston Underground Film Festival, taking home the best picture award, there’s something about Trash Fire that defies description. My gut reaction walking out of the Brattle late Sunday night was the need to call every member of my family, tell them I love them, and forgive me for whatever insignificant harms they may have done me when compared to what I’d just witnessed. Trash Fire is a nasty piece of business and it offers up a heaping dose of pitch black comedy wrapped in a blanket of nihilism. It makes a ballsy move of offering a pair of protagonists that are not only unlikeable but are indeed reprehensible human beings that appear to without possession of the slightest hint of a redeemable character trait. Yet while Trash Fire is often a difficult watch, it’s also an essential watch, and as he has with Excision and Suburban Gothic, Bates continues to dance around horror conventions, blending a number of genres together with a precision that creates intoxicating cinema.

Owen and Isabel (Adrian Grenier & Angela Trimbur) find themselves trapped in a toxic relationship with one another. It’s not just that they can scarcely find a kind word for one another. Every insult they toss at one another is crafted to cut to the other to their emotional core with maximum impact. They can’t even have the cathartic, angry sex that keeps ill-suited couples together far past the expiration date of the relationship. Sexy talk contains zingers like “Is everything okay? You usually don’t last this long.” “It’s been 30 seconds.” “I know.” Isabel openly pines for the days where Owen’s drinking left him too limp dicked and wasted to have sex while Owen openly mocks Isabel’s friends right to their face. It’s an ugly, unsalvageable partnership that’s an endless procession of slammed doors and spilled tears.

When Isabel learns she’s pregnant, Owen’s reaction in next level horrible. Think going dutch on a date, except instead of a restaurant check, you’re splitting the cost of a medical procedure. Yeah. It’s that fucking bad. In hitting rock bottom, Owen makes a promise to recommit. Isabel agrees under one condition: the two of them make a trip to his grandmother’s house in order for him to reconcile with her and his sister. Despite Owen warning her that his grandmother may be the only person on the planet more unpleasant than him, she insists on the trip. A house fire years before killed his parents and left his sister Pearl (Anne Lynne McCord) covered in third-degree burns and put the well being of the two siblings in the hands of their hellfire-and-brimstone spewing grandmother Violet (Fionnula Flanagan). While Owen managed to escape, he left Pearl to fend for herself, and as a result, he has not spoken to either in many years.

Trash Fire is a nasty piece of business and it offers up a heaping dose of pitch black comedy wrapped in a blanket of nihilism.

The introduction of Violet and Pearl boosts the film up a whole other notch. Flanagan embodies the persona of an aged southern belle turned rancid with religion and moral superiority. Violet has used her decades on Earth to hone her skills at finding a person’s week spot and targeting it without mercy. There’s also layers to her villainy that reveal themselves over a long stretch of time. Her acid tongue covers for a mind eroded by year’s of puritanical religious fervor, marking her as a woman that presents a true danger for Owen and Isabel. She worships the angry, judgmental god of the Old Testament, and sees it as her moral duty to strike down and exterminate the sinners, fornicators, and blights that cross her path. Flanagan does an amazing job at allowing her character’s cool, sour demeanor mask the bottomless well of depravity.

Made unrecognizable in prosthetic makeup, McCord more than holds her own as the tragic burn victim. While the fire may have sapped her of her looks, it’s the year’s spent under the warped care of her grandmother that robbed Pearl of her sanity. Pearly scampers about the house unseen and develops an unhealthy obsession with Isabel right away. There’s so much that’s tragic about Pearl because of the four primary characters, she seems to be the only one to understand how twisted each of them all are.

TRASH FIRE blends the straight forward trappings of a romantic comedy with gothic horror. Bates has delivered a similar style of cringe-inducing banter with his previous film Suburban Gothic. However, where that film went for big laughs, the tone set here creates pangs of discomfort deep in the stomach of the viewer. The abrasiveness of the characters is underscored by the low levels of lighting of the film’s first half. Grenier and Trimbur are kept in the shadows, obscuring their expressions while their stylishly decorated apartment seemingly repels natural light. Also helping along the sense of impending doom is Steve Damstra’s wonderful, minimalist score.

Bates offers up one of the most compelling examinations of depression in a movie. He understands how mental illness can twist its tendrils inside a person’s brain, holding it in a vice grip and causing the most vile aspects of a person’s psyche to rise to the surface and destroy anyone that comes into their path. Reflecting back on Trash Fire, the religious tenet of Calvinism’s predestination springs to mind. The idea that depression puts one on a path they cannot escape. When you’re depressed, you know, deep down, that any choice you make is going to be the wrong one, so it’s easy to just stay the course. It’s a ruinous road where one knows the choices they should make in order to right themselves, yet they lack the energy and will to make even a small change that could help them. It’s tragedy in slow motion, and like a car crash you see coming before it even happens, it’s impossible to turn away from.

Beautiful, caustic, tragic and horrifying are only a few of the words that spring to mind when describing Trash Fire. It’s a film that defies expectations given the cast and premise. It has the ability to embrace and repel the audience, often at the same time. While there might not be a wide embrace for a film that has such low regard for humanity, it’s a blessing that a large enough audience that can appreciate what Trash Fire does for the film to exist in the first place.