"Home Is the Hangman" is a story about a man who doesn’t exist who is hired to kill a person who isn’t alive. I hope you are asking yourself how could this be?, because that is what I’m about to explain.

First, the nameless protagonist, who calls himself John Donne in this story, is certainly real flesh and blood, but he has no official identity. He was one of the computer experts who developed the Central Databank Project, which created a virtual model of the Earth and (ideally) everyone in it. Once put into operation, it was possible to locate anyone on the planet by querying a remote access terminal. Although he helped to create it, Donne did not want citizenship in this new world and made sure that he was never put into the program. This is what makes him particularly useful to a certain detective agency, because he is capable of assuming any number of other identities. What is most important in this job, however, is his computer expertise, because the person he must find—and destroy, if necessary—is a machine.

The Hangman is the most highly developed member of a class of machines called telefactors. Telefactors are remote-controlled, often human-looking, devices which move by mimicking the movements of a human wearing a special suit. This exoskeleton provides the operator with visual, audio, and tactile information sent from the telefactor to create a virtual representation of the machine’s environment. The devices were created to allow fragile humans to remain in orbit, while their sturdy, mechanical bodies explored the surfaces of dangerous planets. This puppeteer arrangement worked well with the near planets of the solar system, but economics demanded that operators remain on Earth when telefactors were sent to explore the more distant planets and moons.

The machines were soon incorporated with modeling systems which anticipated action under most situations and were able to compensate for the enormous lag-time between transmissions. They had now become semi-autonomous robots which worked well enough, but were still less than satisfactory. The Hangman was the result of a special project, the goal of which was to create a fully autonomous robot and eliminate all need for a human operator. It was designed with a "brain" containing ten billion "superconductive tunnel-junction neuristors" which mimic the firing of human brain-cells.

Rather than hardwire the inconceivable number of connections, the Hangman’s creators repeatedly passed data signals through its brain and allowed it to form its own paths according to tendency—again mimicking the function of the human brain. The machine was raised as a child and taught through experience, initially being controlled as a telefactor unit and gradually given free rein as it learned. The Hangman’s communications systems were so sophisticated that they allowed it to receive both the directions and background thoughts of its four operators, so that it mirrored the minds/personalities of each.

When the Hangman had been sent to the moons of Saturn and developed sufficiently, it suffered a schizophrenic breakdown, and all contact was lost. Years later, the Hangman’s spacecraft returns to Earth, and the former teleoperator nearest the landing site is murdered shortly thereafter. Donne is enlisted to stop the Hangman and to learn how best to protect the remaining operators. His investigation leads him to each of the three living operators scattered across the country, giving him plenty of travel-time for philosophical thought and plenty of opportunity for philosophical discussion.

Zelazny discusses everything from the beginnings of artificial intelligence to Teilhard de Chardin’s ideas on the continuation of human evolution through artifacts. He includes the obligatory (but not gratuitous) comparison of the Hangman to Frankenstein’s affront to the laws of God and Nature. He also spends several paragraphs questioning the propriety of those who believe in a technological solution for all of life’s problems—quite eloquently. What may be most interesting is that the Hangman turns out to have a better understanding of human nature than most of the human characters.