At Blackwood Manor in 19th-century Providence County, Rhode Island, the esteemed wildlife painter Lord Emerson Blackwood reluctantly commits an atrocious act by bludgeoning his housekeeper to death in the basement. In a desperate attempt to appease the unearthly beings haunting his home, he removes the teeth from both her and himself, offering them to the mysterious creatures dwelling within an ash pit of an ancient fireplace. To his horror, they reject this offering, demanding only the teeth of children. In his anguish, Blackwood pleads for the return of his kidnapped son, only to be consumed by the very creatures he sought to appease.
Fast forward to the present day, 8-year-old Sally Hurst arrives in Rhode Island to live with her father Alex and his girlfriend Kim, who are in the process of restoring Blackwood Manor for sale. Plagued by the recent upheaval of being forcibly taken away from her mother, Sally grapples with her depression, exacerbated by the excessive medication she's been prescribed. Unbeknownst to everyone, a haunting melody emanating from Sally's nightlight awakens the malevolent creatures once more. The following day, she hears the creatures summoning her name, leading her to discover a sealed fireplace adorned with the warning, >"BE AFRAID," inscribed in ancient runes.
Curiosity outweighs caution as Sally opens the fireplace, unearthing one of the housekeeper's lost teeth. Soon, the creatures reveal their sinister nature, stealing Alex's razor and viciously shredding Kim's clothing. After Alex finds a 19th-century silver coin in Sally's possession—something she claimed to have found under her pillow after the tooth vanished—he, in a fit of frustration, chastises her. Determined to communicate with the creatures, Sally ventures to the basement, but Mr. Harris, a worker at the manor, abruptly sends her away, attempting to seal the fireplace. Tragically, the creatures retaliate violently, leaving Mr. Harris hospitalized.
In the hospital, Kim learns from Harris that the key to understanding their torment lies within the unpublished artwork of Lord Blackwood, which she must seek at the local library. The artwork depicts a creature resembling tooth fairies—crafty beings that can transform humans into their kind. As the creatures make another menacing attempt on Sally, it becomes apparent that their leader is a transformed Lord Blackwood himself. Kim bravely discovers a previously unseen mural that portrays Blackwood's son being abducted by these vile entities. In an intense confrontation at the library, Sally fights off the creatures with her camera flash, exploiting their fear of the light and even vanquishing one.
As the tension escalates, Alex and Kim attempt to escape Blackwood Manor with Sally, but they fall prey to the creatures' ambush, rendering them unconscious. Upon regaining consciousness, Sally finds herself bound as the creatures intend to drag her to the basement for transformation. In a twist of fate, Kim awakens and manages to free Sally, but tragically succumbs to a horrific injury as she becomes ensnared in the ropes, ultimately being dragged into the fireplace by the creatures. In a fit of rage and sorrow, Sally crushes the creature who once was Lord Blackwood, marking the loss of her loved ones.
Some time later, Alex and Sally return to the desolate mansion to leave behind a heartfelt drawing of Kim. However, as they depart, a gust of wind carries the drawing into the creatures' lair, now locked with metal. It is revealed that Kim has been transformed, and as the creatures plot their emergence, she cleverly advises them to remain hidden, assuring them that they "have all the time in the world" and that others will inevitably come to Blackwood Manor.
