Andrew MacBane is living in at expensive private quarters at a university, funded by his banker uncle, Arthur Porter. Arthur comes to see his nephew, warning him that he's spent three years wasting his time and living off of Arthur' money. Andrew's friends Elie Green and Mickey Standish arrive after their graduation, and Andrew explains that Arthur is planning to cut him off. Arthur gives his nephew six months to get a real job rather than wasting his time studying witchcraft and leaves. Andrew then grabs a tome and chants a spell, and says that his uncle is now bursting into flames on the stairs. Elie goes to check but reports that Arthur is fine. Arthur says that his ancestor, Jedediah, was a warlock with the power to eliminate his enemies from a distance. However, he killed his wife and closest friends before he was burned as a witch, and the ten diary pages that explained how Jedediah it have gone missing. Andrew's friends say that he should get a job to keep his money, but Andrew insists that he'll find the missing pages.
A few months later, Elie and Mickey return to visit and discover that Arthur is there with Andrew. The uncle informs his nephew that he's been disinherited and promises to make it official when the bank opens the next time. The banker leaves and walks across the campus, but something with glowing red eyes emerges from the bushes and attacks him. In Andrew's quarters, they hear Arthur's screams but Andrew simply smirks and dismisses them as the wind. Elie hears something scratching at the door and goes to investigate, but finds nothing outside.
After sharing a drink, Elie and Mickey leave Andrew's apartment and walk across campus. As Mickey complains that Andrew has no future, they find Arthur's body. Something has ripped out his throat. They run back to Andrew's apartment and find their friend burning book pages in the fireplace. Andrew casually dismisses the news of his uncle's death, and is more interested in the fact that he is now rich.
Later, Ellie meets Mickey at the airport as the latter leaves for a new job in Chad. He informs his friend that Andrew has moved into the MacBane Manor in Boston, the same home that Jedediah resided in. They talk about Arthur, and the fact that the coroner reported it as a wild animal attack, and Elie believes there was more to it than that.
That night, Arthur is in the study of the manor, screaming at an unseen presence to stop.
Elie returns to his apartment as a messenger gives him a telegram. As he goes inside, he hears a scratching noise at the door but finds nothing outside. The telegram contains a message from Andrew, telling Elie to warn Mickey that his life is in danger. He calls Mickey's mother, who tells him that her son was killed by a leopard. A creature outside the door growls menacingly, and Elie hastily grabs a suitcase and leaves. The lights go out in the hallway before the elevator can arrive, and he runs down the stairs. All of the doors are locked, and he finally goes to the basement to try to get out the barred window. When he's unable to open them, Elie retreats to the door, but a menacing figure with glowing red eyes appears at the window and starts to pull apart the bars with its bare hands. The grad student stares in horror and then faints. He wakes up the next morning and discovers that he is unharmed, and that the creature left for unknown reasons.
Traveling to Boston, Elie visits MacBane Manor. Andrew ushers him into the study and locks the door, and explains that he found the missing pages. Elie realizes that he was burning the pages the night that Arthur die, and Andrew admits that they contained a spell that he used to invoke the creature that killed Arthur. He explains that the spell summons a creature from the darkness, loyalty to the MacBanes and whoever casts the spell. It kills whoever it is sent after, but then demands a price of another victim. None of the pages contained a banishing spell, and Jedediah was only able to banish it temporarily back into the darkness. The other pages of the diary related how Jedediah was forced to sacrifice his wife and friends to the creature rather than lose his own life. Andrew explains that the creature came for him, and he gave it Mickey instead. When it demanded Elie's life, Andrew initially gave in but then had second thoughts and managed to recall it at the last second.
As the two men listen, the creature starts scratching at the doors. Andrew warns that it's too strong for the doors to stop it, and explains that it is the embodiment of all the jealousy of mankind. The creature smashes through the doors and Andrew goes to confront it, telling it to return to the darkness. Elie stares in horror as Andrew commands the creature to burn. It grabs its summoner, killing him, and then bursts into flames. As Andrew's manservant comes in, asking where his master is, Elie tells him that there are no more MacBanes.