Roderick Usher returns to his ancestral family estate after years away, hoping to find respite from his many afflictions within the crumbling, gothic halls of the House of Usher. But he soon realizes a malevolent darkness permeates both the estate and his own tortured bloodline.
Roderick reunites with his kindhearted twin sister, Madeline, who now resides alone in the decaying mansion. She tells Roderick that their father committed suicide years ago after descending into madness, hinting at a sinister legacy Roderick tried to escape. Despite Roderick’s fragile mental state, Madeline convinces him to stay and restore the estate to its former glory.
Roderick begins having disturbing visions of ghostly figures stalking the mansion’s decrepit ruins. Madeline fears Roderick has inherited their family’s curse of madness. Local townspeople whisper rumors that the Usher estate is haunted by generations of tortured souls.
As Roderick struggles against his growing madness, he discovers cryptic documents written by his ancestors which seem to implicate the Usher bloodline in dark occult practices and demonic pacts. A trepanation kit found in their father’s old study suggests a history of twisted medical experiments.
When Madeline suddenly falls ill, Roderick’s nightmares worsen, blending reality with visions of Madeline’s premature burial. During this descent into delirium, Roderick unearths hidden passages beneath the mansion, leading to a secret vault filled with abominations hinting at the true nature of the Usher legacy.
In his investigation, Roderick learns that his ancestors used the occult to try to achieve immortality by merging their souls across generations. But they unleashed evil forces they could not control, dooming the Ushers to madness and corruption. The ghosts Roderick sees are the twisted remnants of his ancestors.
As Madeline nears death, Roderick becomes obsessed with continuing his family’s immortality experiments to save her. Using occult texts from the vault, Roderick intends to merge his soul with Madeline’s, though she begs him not to for fear of the consequences.
In a climactic ritual during a violent thunderstorm, Roderick merges his spirit with Madeline’s before her last breath. As he does so, a portal opens, allowing horrors from beyond into the House of Usher. The demons his ancestors summoned now rise to take their due.
With his soul fused to Madeline’s, Roderick watches in helpless horror as the demons lay waste to the mansion and dead Ushers rise from their graves to join the infernal fray. As the estate crumbles and burns, the truth finally becomes clear to Roderick—his family’s thirst for immortality led to their eternal damnation.
Madeline’s spirit appears to Roderick within the flames. As the cursed souls of the Ushers are dragged to Hell by the vengeful demons, she sadly tells Roderick their souls will never find peace. The two vanish together into the fire as the House of Usher is finally consumed, condemning the Usher line to the Hell they made for themselves