A Monster Calls is a fantasy novel by Patrick Ness about a boy named Conor and his relationship with a monster who visits him at night. Conor's home and school life is unpleasant and his mother is dying of cancer. One night after being awoken by a nightmare, Conor meets a monster in his room who begins telling him stories in exchange for telling his nightmare. The monster's stories center around entangled human relationships and Conor's story of his nightmare helps him to confront his fears and heal.
The story opens with 13-year-old Conor O'Malley waking from the same nightmare he has been experiencing for the past few months, "the one with the darkness and the wind and the screaming". At seven minutes after midnight (12:07), a voice calls to him from outside his bedroom window, which overlooks an old church and its graveyard and is sheltered by a yew tree. Walking to the window, Conor meets the monster, a towering mass of branches and leaves in human shape. The monster insists that Conor summoned it, and that it will help Conor by telling him three short stories. In exchange Conor must tell his own story afterward.
The monster continues to meet Conor, almost always at 12:07 am, to tell its stories. Between its tales, which aim to demonstrate the complications inherent in humans, it is revealed that Conor's mother is undergoing chemotherapy and has been afflicted with cancer for the past few months. His father is nowhere to console him, and a cold relationship with his grandmother provides no comfort either. Conor is a victim of bullying at school and he has distanced himself from all other social contact. As the story progresses, his mother's condition worsens.
Conor's encounters with the monster have escalating consequences. While the first story has no real impact on Conor's life, the second story leads to being blamed for the monster vandalising his grandmother's living room, and the third leads to physically assaulting Harry, the school bully, after brief possession by the monster.
When he is forced to tell his own nightmare, however, Conor finally begins to confront his feelings. Ultimately the monster comforts him, revealing that its purpose has been to heal him. The novel closes with Conor accepting his mother's imminent death and the changes it will bring to his life. At 12:07, his mother dies in the hospital.