n 1981 Blackeberg, Stockholm, Oskar may be a 12-year-old boy who lives together with his mother, who is loving and with whom he initially seems to possess an in depth connection. His father, whom Oskar visits occasionally, is an alcoholic living within the countryside. Because the boy is that the victim of merciless bullying, Oskar has gained morbid interests, which include crime and forensics, and he keeps a scrapbook crammed with newspaper articles about murders.

 One day, he befriends Eli, a woman of about an equivalent age, who just moved in nearby . She lives with an older man named Håkan, a former teacher who was fired when caught in possession of kid pornography. She's revealed to be a vampire who was turned as a toddler and is therefore stuck forever during a young body and mind. Oskar and Eli develop an in depth relationship, and she or he helps him fight back against his tormentors. Throughout the book their relationship gradually becomes closer, and that they reveal more of themselves, including fragments of Eli's human life. Among the small print revealed is that Eli may be a boy named Elias who was castrated when she was became a vampire over 200 years ago. However, she dresses in female clothing and is perceived by outsiders as a lass .

 Håkan serves Eli, whom he loves, by procuring blood from the living, fighting against his conscience and selecting victims whom he can physically trap, but who aren't too young. Eli gives him money for doing this, though Håkan makes it clear he would roll in the hay for nothing if she allowed them to be physically intimate. Håkan offers to travel out one last time under the condition that he spends an evening with Eli after she gets the blood, but with the caveat that he may only touch Eli.

 Håkan's last plan to get blood fails and he's caught. Just before capture, however, he intentionally disfigures himself with acid in order that the police won't be ready to trace Eli through him. When Eli finds him within the hospital, Håkan offers his blood and is drunk dry while sitting on the window ledge, but a guard interrupts them and Eli fails to kill him. in order that he won't also find yourself becoming a vampire, Håkan throws himself out of the window to the bottom below. Despite this, he reanimates as a mindless vampire driven only by his desire for Eli. Håkan then relentlessly pursues Eli, managing to trap her during a basement before trying to rape her, but she fights him off and escapes. Later, the wounded Håkan is destroyed by Tommy who accidentally gets locked within the basement with him.

 Meanwhile, Blackeberg local alcoholic Lacke suspects a toddler is liable for the murder of his ally , Jocke (whom Eli has killed for blood). Later, Lacke witnesses Eli attack on his sometime-girlfriend, Virginia. She attempts to drink her blood, but is fought off by Lacke. Virginia survives, but starts turning into a vampire. She doesn't realize her "infection" until she tries to prolong her life by drinking her own blood, and finds that exposure to the sun causes boils on her skin. Upon being hospitalized, Virginia realizes what she has became and kills herself in her bed by deliberately exposing herself to sunlight . Lacke, while attempting to avenge Virginia, is thwarted by Oskar and Eli.

 Oskar eventually fights back and injures his tormentor, Jonny, that the boy's older brother Jimmy hunts down and attempts to harm Oskar in retaliation. Oskar further incurs their wrath when he sets fire to their desks, destroying a treasured photo album belonging to their father. They corner Oskar in the dark at the local swimming bath and plan to drown him. However, Eli rescues Oskar and decapitates the 2 brothers; together they flee the town with Eli's money and possessions.