An unpopulated city on a planet far from Earth.
The City - An unpopulated city of the Taollans, created to exact revenge on Earth.
Captain - Head of an Earth rocket expedition.
Smith - A crewman on the Earth rocket who fears the city.
Jones - A crewman on the Earth rocket.
Jensen - A crewman on the Earth rocket.
Hutchinson - A crewman on the Earth rocket.
Springer - A crewman on the Earth rocket.
The City, which seeks revenge on Earth for killing its people twenty thousand years earlier.
The crew of the Earth ship which lands on this city.
The City confirms these people are indeed from Mars and kills them.
Re-animating the corpses, the City sends the Earthians back to their home planet to deliver disease bombs like the one that killed its population.
The main theme is revenge: the city is designed to kill Earthians when they finally arrive, something it waited twenty thousands years to happen. The inhumanity of the city's objective is reflected in the total lack of inhabitants, as well as the way it exacts revenge on Earth by turning the humans into life-like robots bringing doom to their home planet. A related theme is the abuse of technology. The city is a tool of revenge and seems to take a very human, emotional thrill in completing its objective. After it does so, however, it has nothing left to do and dies. One may see this as achieving a deserved peace, but it also shows the emptiness of revenge once achieved. The city is corrupt in that it has ceased being a home for people - the true function of any city - and instead exists to destroy the homes of others.
The city waited for twenty thousand years but finally a rocket arrives, one manned by travelers from Earth. The crew's captain warns the men to be careful, but Jones argues that the city is dead and requires no concern. The city's senses speak to each other, as the Ears and the Nose take in information about the visitors and asks the Eyes to watch them as they explore. Smith senses something familiar about the place, despite the fact that it's billions of miles from Earth and they have the only light-year rocket in existence. Smith begins to panic as the city comes fully awake. He runs back to the rocket and the captain chases after him - however, the city traps the captain and rips him open with precision.
The city verifies these men are the enemies, the Earthians who declared war on its native people, the Taollans, twenty thousand years ago; these Earthians fled to another galaxy after it laid waste to the world with disease. The city fills the captain's dead body with artificial parts before sewing him back together. He then re-appears on the city street and shoots Smith dead. The other men are shocked as the city speaks through the reanimated captain, explaining its people's revenge after twenty thousand years and two false alarms with other visitors. The men think the captain is sick, but the pavement gives way and the city does to these men what it did to the captain. Soon, these men - now artificially reanimated tools of the city - head back in their rocket with disease bombs, which they will drop on Earth. Having performed its mission, the city finally allows itself to die.