Ghost hunter Cyrus Kriticos and his assistant Dennis Rafkin embark on a thrilling mission to capture a powerful spirit known as the Juggernaut within a junkyard. During the intense struggle, they face horrific losses, including Cyrus himself. Despite the chaos, the team successfully manages to trap the ghost.
Meanwhile, mathematician and widower Arthur Kriticos receives surprising news from the estate lawyer, Benjamin Moss, that he has inherited a grand mansion from his uncle Cyrus. Eager for a fresh start, Arthur, along with his financially troubled family—which includes his children, Kathy and Bobby—decides to move into this new home, accompanied by their babysitter/nanny, Maggie.
As the family tours their new residence, which is a marvel made almost entirely of glass, they are entranced by its stunning design, featuring etched Latin phrases and priceless artifacts. However, their excitement quickly turns to concern when the children venture into the basement and encounter several ghosts. In a state of panic, Dennis rushes upstairs to warn Arthur about the dark history of this house. Doubting Dennis' credibility, Arthur listens instead to Benjamin, who reassures him that Dennis is overreacting. However, the truth is soon revealed when Dennis reveals there are twelve spirits trapped within the walls of the house, secured by arcane spells.
Benjamin soon reveals his true intentions when he sneaks away to collect a bag of money meant for payment. This reckless act activates one of Cyrus' deadly mechanisms, sealing the entrance and releasing the imprisoned spirits. In a horrifying encounter, he meets the Angry Princess, who gruesomely takes his life.
Arthur’s skepticism about spirits is put to the test when he witnesses a terrifying attack on his daughter by the ghost known as the Jackal. In the chaos, Bobby goes missing after separating from Maggie, inadvertently wandering into the basement filled with aggressive spirits like the Torso and the Bound Woman. Amid the fray, Arthur manages to find Kathy and faces the Jackal with her by his side. They are aided by Kalina Oretzia, a spirit liberator who helps Arthur rescue his daughter, though not without peril as she temporarily loses her in the midst of the battle.
Determined to save his children and escape this nightmare, Arthur learns from Kalina that the house is not just a home; it's the Ocularis Infernum, a complex machine created by Cyrus that channels the power of the dead. In a shocking twist, Arthur discovers that the spirit of his deceased wife, Jean, is one of the ghosts fueling this abominable invention. Kalina warns him that his children are in extreme danger, and the only way to save them is to sacrifice himself as the 13th ghost. His selfless act of love could dismantle the machine's evil force.
The twist thickens when Arthur discovers that Cyrus has faked his death and is alive, plotting behind the scenes. Kalina, revealed to be his loyal partner, knocks Maggie unconscious, revealing their entwined fate. The dark plan unfolds further when Cyrus orchestrates a scheme to trap Arthur into becoming the 13th ghost, using his children’s capture as bait.
In a desperate struggle, Arthur and Dennis attempt to save Kathy and Bobby, aided by a makeshift wall that Dennis ultimately uses as a shield to protect Arthur at the cost of his own life. As chaos ensues, Dennis faces his end at the hands of the Juggernaut, leaving Arthur to confront the devastating truth.
Caught behind glass, Arthur receives an ethereal visit from Jean’s ghost. Just then, all the spirits vanish in response to a tape playback from Cyrus. Meanwhile, Kathy and Bobby are perilously caught at the center of lethal spinning rings. In a final showdown, Arthur faces off against Cyrus, interrupted by Maggie’s desperate attempts to shatter the machine. As the machinery begins to fail, it triggers a release for the ghosts, who swarm Cyrus and exact their revenge.
In the climactic moment, Arthur bravely leaps into the fray to save his children, completing a harrowing escape as the glass walls of the house come crashing down, liberating the spirits. Only a peaceful Jean remains momentarily to bid farewell to her family before she, along with the others, moves on.
The film concludes with a weary Maggie emerging from the ruins, proclaiming, “I quit!” as the echo of their harrowing adventure lingers in the air.
