"Dark Maidens" is a mystery and psychological thriller manga that revolves around a group of high school girls who are members of the prestigious literary club at Shinyo Academy. The narrative begins with the sudden death of Itsuko Tamiya, the club's president, who falls from the school rooftop under mysterious circumstances. The incident is initially ruled a suicide, but the remaining members of the club suspect foul play. Each girl harbors secrets and personal grievances, creating an atmosphere of tension and mistrust.

The story unfolds through a series of interconnected flashbacks and present-day events, as the club members gather to read a manuscript left behind by Itsuko. The manuscript, titled "Dark Maidens," is a fictionalized account of their lives and relationships, revealing hidden truths and unresolved conflicts. As the girls take turns reading the story aloud, they begin to uncover clues about Itsuko's death and the possible involvement of one or more of them.

Key characters include Ruri Asami, the new club president, who struggles to maintain order and uncover the truth; Ayano Fujisaki, a quiet and introspective girl with a troubled past; and Mako Kurosawa, a sharp-tongued and cynical member who often clashes with the others. Each character is intricately developed, with their motivations and secrets gradually revealed as the story progresses.

The narrative delves into themes of betrayal, guilt, and the complexities of human relationships. The girls' interactions are marked by a mix of camaraderie and rivalry, as they grapple with their own insecurities and the weight of Itsuko's accusations in the manuscript. The mystery deepens as the lines between fiction and reality blur, with the manuscript seemingly predicting events and exposing hidden truths about the club members.

As the investigation into Itsuko's death progresses, the girls are forced to confront their own roles in the tragedy and the darker aspects of their personalities. The story builds to a climactic revelation that ties together the events of the manuscript and the real-life circumstances leading to Itsuko's demise. The resolution leaves lingering questions about the nature of truth and the consequences of their actions, creating a thought-provoking and emotionally charged conclusion.