Martin Durant, a police officer and principal character of the story, chases two murderers into an alien forest where intrusion is restrained by terror and forbidden by vigorously enforced U.S. law. He kills one murderer while the other flees to face the terror of the forest. Intensely curious he resolves to remain in the forest, despite direct orders to leave, to try and discover why its inhabitants are so feared. He shortly observes that the feared aliens glow in iridescent colors, induce paralysis and psychosis in humans and gradually disappear. Durant learns the hard way that his own emotions, amplified, distorted and reflected back to him, are the sources of the glow and the paralysis. He realizes that chance and a rash but now irreversible decision have forced him into a dilemma far beyond his understanding. He has also reached the conclusion that the aliens are not the malevolently intelligent creatures human superstition has made them. But now he neither can return home nor emerge from the forest and reveal what he has learned for fear of exposing these simple beings and their verdant home to exploitation or abuse. He walks through the forest, a journey of six weeks, and telephones his girl friend who by this time, along with everyone else, has presumed him dead. Following a tearful and impassioned reunion, the two of them decide to seek advice from a much admired former professor of theirs. The three of them meet in a remote town and hatch a plot to fake Durant's psychosis in a sanitarium while he and his girl friend endure months of intense study in preparation for returning to the forest to try to understand the links between human emotions and the paralysis and madness inadvertently induced by the aliens. Enduring paralysis and terror, they learn the causes of both, and recognize the implications for unraveling the intricacies of their own minds. They leave the forest, travel to Washington DC to entreat Congress to repeal the law forbidding entry into the forest. The couple are then married on Mt. Tamalpais north of San Francisco. Superstitious fear succumbs to an intense search for the as yet undiscovered human capacity for telepathy serendipitously revealed by the aliens. Struggles emerge in the book not in physical contests between individuals, but in confrontational dialogues that discuss opposing ideas like, for example, courage versus fear, reason assaulting superstition, and freedom of thought opposing its eternal enemy, ignorance armed with authority. Eshen, a distant planet and a colony of the United States, and its alien inhabitants furnish the stage for this dramatic love story.