Interlopers is a 2001 science fiction novel by Alan Dean Foster. The story centers on Cody Westcott, a young archeologist, who returns from a dig at Apachetarimac having studied the Chachapoyansthat race. In an attempt to reconstruct an ancient potion whose ingredients he discovers in the dig, his friend is murdered and he ends up drinking the only sample. He discovers that he can "see" strange creatures inhabiting the world, and that these creatures harm humans and cause feelings of hate and anger upon which they feed and multiply. These "Interlopers" or "Those Who Abide" also realize he can see them at the same time, and begin to conspire against him in order to stop his interruption of their feeding. They go so far as infesting his wife with numerous powerful Interlopers, and Cody must ally with an ancient society and visit several sites of mythical power in order to free her and bring a halt to the Interlopers' plans.