The film follows members of a damaged family before they reunite at their remote farmhouse, where they will confront long-buried secrets and sins of the past.

Thomas "Tommy" Graham is a man with intellectual disability who lives on a farm in Texas with his abusive and alcoholic father Josiah.

The assemblyman they contact for assistance informs them that the Graham property has a troubled past, due to Josiah's wife Miriam hanging herself in their garden several decades prior.

The next day, Josiah tells Tommy that Miriam's spirit visited him while he was asleep and told him that they need to right their ways to save her from hell.

Eli is forced to accept a job from Boone, a bartender and criminal, to steal some Nazi gold from a band of Romani in exchange for his record being cleared and his debt being settled.

The agent expresses concerns about the couple filing for separation six years ago, and asks Mary if she would be open to psychiatric evaluation.

That night, the three siblings sit together with Josiah, and it is revealed that Tommy has been repeatedly and unknowingly violating his restraining order against his ex-wife and their son Tanner.

The website's consensus reads: "What Josiah Saw may be too unrelentingly unpleasant for some viewers, but this slow-burning look at generational trauma leaves a lingering, nightmarish impact.

"[9] Andrew Mack of Screen Anarchy also gave the film a positive review and wrote, "Robert Patrick is an absolute force to be reckoned with.

"[12] The Guardian's Phil Hoad gave it 4/5 stars, writing, "What Josiah Saw isn’t quite as accomplished as Pulp Fiction, whose intersecting trajectories and penchant for petty criminal sleaze it shares.

"[13] Brian Costello of Common Sense Media gave the film 3/5 stars, calling it "a good but not great movie that seems like it has a shot at attaining cult status, as it's likely to reward repeated viewings (assuming one would want to do such a thing, considering what transpires in some of the more shocking scenes)", but said it was "damaged by too-long scenes involving traveling Romani who are portrayed stereotypically."

He concluded, "It's maddeningly close to being a great movie, but these forays into the Tarantino-esque (particularly with the second vignette) make the whole thing feel less inspired than the rest of it.

Club gave the film a negative review and wrote that "the writer-director piles deviancy on top of taboo until your trauma receptors go numb.