Teenage twins Rachel and Theo travel to Auckland to stay with relatives following the sudden death of their mother. Where there was once a psychic bond between them, now there is a rift as Theo, particularly, refuses to confront his grief. Rachel reaches out to him, but is rebuffed. Staying with their Aunt Kay and Uncle Cliff on Lake Pupuke, the twins are fascinated by the volcanic lake and the smell that seems to come from the creepy old Wilberforce house around the shore. They visit Mt. Eden, where Theo sees Mr. Jones, a strange old man from whose hands fire seems to glow. When it seems the twins are being watched - and that the Wilberforces can smell them - Theo resolves to investigate the Wilberforce house. Inside, he and Rachel find what can only be an alien environment. They overhear Mr. Wilberforce talking about something stirring beneath the ground. He says he will kill the twins if they find "the fire-raiser." Rachel is alarmed and reaches out to Theo but, terrified of getting close to anyone since his mother's death, he pushes her away and sets out alone to find the fire-raiser - the man he saw on the mountaintop.