The Wall
Clayton describes The Wall in the following passage: "The Wall was the largest man-made structure on the planet. It towered fifty meters above sea level and looped all around the top of the world, enclosing northern Europe, northern Russia and Canada.” The immensity of the wall is emphasized here, and there is a sense that people are trapped within. She describes how "On the top were three rows of electrified razor wire that would cut a rhino to ribbons", which gives the wall a threatening impression.
The yellow dust
The civilians of London are told that the world beyond the world has been infested with a yellow “poisoned dust.” The dust was used to kill the animals when they turned mad, and kills every living thing it comes into contact with. This dust symbolizes the corruption and decay that exist in this society, as a small group of powerful men continue to exploit people.Later in the text, Ellie and Mika discover that there is no yellow dust, and that the government have lied to them in order to ensure they remained oppressed.
Animals
Growing up, Ellie learned about the Animal Plague, an event in which all animals went insane and started killing people: “she had grown up hearing its story until it was as familiar to her as the ones her mother read at bedtime". Ellie remembers that “instead of friendly animals having happy adventures, it involved insane animals on a murderous rampage; animals that ripped the doors off cars to kill the people inside." Ellie feels sorry for the animals, which tells us she is a kind and sympathetic person.
Evil
Mal Gorman is an embodiment of evil in the book, and he kidnaps Ellie in order to use her psychic abilities. He is described in the following passage: "there was no love in his eyes, only a cold glint, because he wasn't appreciating their beauty, only how much they were worth." Here the “cold glint” in his eye reveals that he is emotionally cold and heartless. He sees the children for how much they are worth and does not value them as people.