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...

Emily and her friends go to Cielis for help, but something is very wrong, and as the number of Stonekeepers gets smaller and smaller, an awful secret is slowly uncovered that means the certain destruction of everything Emily fights for.

Navin journeys to the city of Lucien where he searches for a beacon essential to his fight against the Elf King; while Emily heads back into the Void with Max, one of the Elf King's followers, where she learns his darkest secrets.

When Emily loses control of her Amulet, she is imprisoned in the Void, where she must escape the influence of the Voice, while her brother, Navin, travels to a space station where the Resistance is preparing to battle the approaching Shadow forces.