"Angels of Death" centers around Rachel Gardner, a 13-year-old girl who wakes up in the basement of an abandoned building with no memory of how she arrived there. The building is divided into multiple floors, each controlled by a deranged "executioner" who poses a deadly threat to anyone who enters their domain. Rachel encounters Zack, a bandaged man wielding a scythe, who initially intends to kill her but agrees to form a pact: she will help him escape the building in exchange for her life. Together, they ascend through the floors, facing increasingly dangerous adversaries and uncovering the dark secrets of the building and its inhabitants.

Each floor introduces a new antagonist with distinct psychological issues and violent tendencies. These include Danny, a doctor obsessed with "saving" people through grotesque experiments; Cathy, a manipulative woman who preys on others' emotions; and Edward, a childlike executioner who views murder as a game. As Rachel and Zack progress, their relationship evolves from one of mutual distrust to a fragile alliance, with Rachel's calm demeanor contrasting sharply with Zack's impulsive and violent nature.

The narrative delves into themes of trauma, morality, and existential despair, as both protagonists grapple with their pasts and motivations. Rachel's backstory reveals a history of abuse and a desire for death, while Zack's origins are tied to his violent tendencies and a longing for freedom. The building itself serves as a metaphorical prison, reflecting the characters' inner struggles and the cyclical nature of their suffering. The series builds toward a climactic confrontation that challenges their perceptions of reality and forces them to confront their deepest fears and desires.

The story is driven by its psychological tension and the interplay between its central characters, with a focus on their development and the moral ambiguity of their actions. The series maintains a dark and oppressive atmosphere, underscored by its exploration of human fragility and the consequences of unchecked violence.