Emily and Navin's mother is still in a coma from the arachnopod's poison, and there's only one place to find help: Kanalis, the bustling, beautiful city of waterfalls. But when Em, her brother, and Miskit and the rest of the robotic crew aboard the walking house reach the city, they quickly realize that seeking help is looking for trouble, dangerous trouble.

The Elf King's son, Trellis, is still after them, but this time he's accompanied by a mysterious and dangerous guard, Luger. Then an equally mysterious fox, Leon Redbeard, steps in to help. This new fox friend offers to take Em on the perilous trip up Demon's Head Mountain to find the antidote she needs. Miskit is suspicious, Navin is worried about being left behind, and Emily is in the toughest spot of all. She's got to let loose the power of the amulet—without losing herself!