The Holloway crew, having made it to the Natural History Museum barely alive, continues to seek a cure for the Disease but when the children return to the streets for medical supplies, it is no longer clear who--or what--is their enemy.

Ella is out in the country, alone now except for her silent rescuer, Scarface, about whom she knows nothing, while Ed leaves London on a dangerous quest, determined to find Ella and keep his promise to Small Sam that he will reunite sister and brother.