Robert and his wife, Maia, have just inherited her father's massive estate, and they are thrilled about moving in. Shortly after their arrival, Maia uncovers a secret compartment in the floor that houses an eerie doll. Seeking normalcy, they visit a local bar where they meet Judy, the bartender. The townsfolk are overjoyed to welcome Maia back, showering the couple with drinks. However, Robert overindulges and soon finds himself passed out drunk.
In the dead of night, Robert is stirred by the sound of crying from the attic. Confronted by a very old blind woman who cryptically states, “You’re home,” before unleashing a menacing roar, he realizes it's just a nightmare. The couple soon discusses their shared grief over losing their baby to a miscarriage, with Maia feeling that Robert unjustly holds her responsible.
As Robert explores the attic further, he discovers a painting that bears an uncanny resemblance to him. Though Maia insists it isn't a true likeness, the artwork is titled “The Visitor Accepts,” leaving her puzzled about its origin. They learn of Robert's past battles with anxiety and his reliance on medication, suggesting a man haunted by his own mind.
Visiting a hardware store, Robert is approached by the clerk who insists, “We need to talk, Robert.” However, their conversation is cut short when another customer arrives, prompting her to hurriedly pass him a note that reads: “Art is a lie that makes us realize the truth.” This note leads them to Delacroix Art & Antiques—an establishment that might hold the key to their discovery.
During her father's memorial service, the pastor delivers an emotional speech about his absence, further intensifying Robert's discomfort. Meanwhile, the townspeople exhibit an overwhelming friendliness towards Robert, which feels disconcerting. Robert later visits the antique shop the hardware clerk mentioned, where he encounters another painting that features his likeness. Titled “The Visitor Watches it Burn,” the shopkeeper claims it was on display when she purchased the store. She dissuades him from seeking answers, suggesting he return to London “as fast as your legs can carry you!”
Later, upon returning home, Maia humorously hangs the first painting in their living room, believing it to be a light-hearted joke. Robert begins to speculate that the stress is affecting his judgment. In a startling turn of events, the antique shop owner is visited by an uncanny swarm of locusts, resulting in her demise.
The next morning unveils even more shocking news: Maia informs Robert of her pregnancy. Months fly by, and a conversation with the pastor reveals the dichotomy of Robert's beliefs. The pastor predicts, “You will be... when you see for yourself, you won’t be able to deny it.” He possesses a painting titled “The Visitor Stakes His Claim,” featuring Alistair Edgar, the historic savior of their town. However, the couple faces a bizarre situation when they return home to find their living room teeming with frogs.
Suddenly, Robert receives a disquieting phone call from Maxwell Braun, another art dealer who has been investigating the series of Visitor paintings and photographs. He possesses artworks featuring historical figures like Hitler and Saddam Hussein, revealing how Robert—or the Visitor—has appeared in countless moments throughout history, particularly ones we wish to forget. Maxwell warns Robert that the decision to remain could mean a dark transformation as the Visitor.
Determined not to remain in the town, Robert shares his plan to return to London with Maia, who reacts violently to this news. Afterward, Robert receives a chilling call from Maxwell to meet him in the woods, where he discovers Maxwell's lifeless body bound to a tree. When he returns home, he finds yet another portrait of himself that Maia reveals is of her father—digging deeper into a shocking family secret: Robert was actually kidnapped as a baby, and his life in London was engineered to break a sinister cycle.
In a dramatic revelation, Maia confesses to Robert that he is the one committing murders under the influence of a greater, dark power. This pattern has been occurring since Alistair's pact with the devil in the 1700s. She explains that even their miscarriage had a purpose; Maia is destined to bear a boy to ensure the continuation of the "Robert" lineage. As the intense weight of the truth overwhelms Robert, he loses consciousness, prompting Maia to declare that this is his chance to finally fulfill his predestined role.
Flashing back to their initial meeting in London juxtaposed with Maia giving birth, the atmosphere turns ominous. Townsfolk clad in robes and masks encircle them as the baby is born. Robert, now transformed back into the Visitor, ultimately takes his rightful place on the throne. In the aftermath, Maia fades into blindness, mirroring her mother, and Robert drives triumphantly through the town, celebrating his resurgence with the townspeople.
