Sixteen-year-old Frank Cauldhame narrates the story from a small Scottish isle. While on his way to visit what he calls the “Sacrifice Poles,” he sees a detective named Diggs approaching the door of the house where Frank lives with his father. The Sacrifice Poles serve as Frank’s warning system, alerting him by unknown (to the reader) means to when someone new ventures onto the island. Each pole contains the head of an animal Frank has killed, and he often urinates on them to give them his power.

Frank answers to a type of oracle that he calls the Wasp Factory, which he keeps in the attic loft, where the wasps’ behavior tells him things and answers his questions. After returning to the house, he sees that, as usual, their home is covered in notes that provide the length of household objects, such as tables, drawers, silverware, and more. Over dinner his father tells Frank that his brother, Eric, who has a history of burning dogs on the island, has escaped from a psychiatric hospital. Frank is excited but fearful. He knows Eric will make it to them.