A woman groans and twists with the pains of childbirth in a bedroom that feels stuck in another era, while two elderly women who resemble twins and an older man watch every movement. As the labor reaches its peak, the elder man leads the exhausted mother out of the room, leaving an uneasy hush in the air and questions that will echo through the town.
At Miskatonic University in Arkham, Massachusetts, Dr. Henry Armitage [Ed Begley] has just finished a lecture on local history and the very rare Necronomicon, a book so coveted it is said to exist in only one known copy. He hands the volume to his student Nancy Wagner [Sandra Dee], asking her to return it to the library. She is followed by a stranger who introduces himself as Wilbur Whateley [Dean Stockwell], a charismatic man with a hypnotic gaze that seems to bend Nancy’s will, at least for a moment, as he begs to study the book further. Nancy grants him access despite it being closing time, and the spectral weight of the book’s legend hangs in the air as the two depart.
Armitage has already done his homework on the Whateleys, a family with a deeply troubled history that stretches back through generations. He warns Nancy about getting involved with Wilbur, but his cautions are ignored as Nancy decides to escort Wilbur back to Dunwich after he purposely misses his bus. The ride out of Arkham brings Nancy face-to-face with the town’s wary mood toward Wilbur, a mood that seems almost tangible at a gas station on the town’s edge.
Back at the Whateley house, Nancy meets Old Whateley [Sam Jaffe], Wilbur’s grandfather, a figure wrapped in mystery and menace. Wilbur disables Nancy’s car and drugs her, trapping her in a haze that blurs the line between waking life and dream. Under hypnosis and the lingering effects of the drug, Nancy agrees to spend the weekend with the Whateleys, and she does not change her mind when Wilbur’s companion for the night, Elizabeth Hamilton [Donna Baccala], arrives with Armitage from Arkham the following morning. The trio doesn’t abandon Nancy, but the questions only grow: what is the truth behind Wilbur’s family, why is Lavinia Whateley still alive in an asylum, and what does the town really know about the past?
Through careful, unsettling inquiry, they uncover that Wilbur’s mother, Lavinia Whateley [Joanne Moore Jordan], is alive but aged well beyond her years, confined behind asylum walls. Dr. Cory [Lloyd Bochner], the town physician, informs Armitage that Lavinia delivered twins at Wilbur’s birth—one child was stillborn, and the other grew into the disturbing presence now at the center of these events. The revelation casts a pall over the weekend: the childbirth was traumatic for Lavinia, and the family’s strange fate seems to hinge on that moment in time.
In a secluded, cliffside location by the sea, the drugged and hypnotized Nancy is coaxed into a moment that shifts the balance between safety and doom: Wilbur seduces her on an ancient, weathered altar. Meanwhile, Elizabeth enters the Whateley house, opens a locked door, and inadvertently unleashes a creature—Wilbur’s monstrous twin—which escapes after killing Elizabeth. The night takes on a ritual nightmare quality as the personal and the cosmic collide.
Old Whateley confronts Wilbur and Nancy about Nancy’s car, and in the ensuing argument, the elderly man falls to his death on the stairs. Wilbur drags him toward a cemetery for a startling, non-Christian burial, only to have the townsfolk intervene, refusing to let the desecration pass unchallenged. The tension in Dunwich rises as the twin’s presence grows more dangerous, and Wilbur’s appetite for power becomes clearer.
The conflict reaches its apex when Wilbur fights and kills a guard to steal the Necronomicon, a theft that marks a turning point in the history of the town and its legends. Lavinia dies in the asylum, her appearance aging dramatically, a visual reminder of the toll the events have taken on everyone involved. With the book in hand, Wilbur prepares Nancy for a ritual sacrifice intended to unleash “The Old Ones” and summon a power beyond mortal comprehension. The Whateleys’ estate is swallowed by fire as the ritual unfolds, and Wilbur’s monstrous twin runs amok across Dunwich, adding to the body count.
Confronted by Armitage, Wilbur chants and calls down his demonic father as Armitage chants reverse spells, a desperate bid to turn the tide of a ritual that could erase the town entirely. A bolt of lightning strikes, and Wilbur falls into the sea, seemingly quenched by the very forces he sought to command. Yet Nancy, who emerges physically unharmed, is escorted from the site by Armitage and Cory. They calm her, insisting that the Whateley line has ended, even as a startling truth emerges: Nancy is pregnant with Wilbur’s child, a final, unsettling reminder that some legacies cannot be easily severed.
Throughout these events, the film sustains a measured, patient pace that folds character psychology into a foreboding atmosphere. The relationships between Nancy, Wilbur, Armitage, Old Whateley, Lavinia, Elizabeth, and the other players form a web in which ambition and fear feed a nightmare that resonates long after the flames die down. The story is a careful reweaving of forbidden knowledge, doomed lineage, and the uneasy convergence of small-town life with ancient, cosmic forces, all anchored by a sense of inevitability that something terrible has always been waiting just beyond the edge of Dunwich.
