Seraphina, a dark witch weary of killing, retreats to a shared apartment in Brooklyn, hoping to live an ordinary life. But her vile neighbors, the Cartwright family, torment her relentlessly: piling trash at her door, stealing her Wi-Fi, spreading malicious rumors, and ultimately killing her familiar, a black cat named Nightshade. The cat's death pushes Seraphina over the edge. She unleashes her dark powers and casts the "Mark of Greed," which forces the evildoers to be unable to lie or harbor evil intentions. Trapped in nightmarish illusions that make life unbearable, they end up digging their own graves. In the end, the entire family is either imprisoned or committed to a mental hospital. Nightshade is resurrected through their familiar bond, and Seraphina buys the entire apartment building, establishing her own domain.
