A five-thousand-meter starship; a dying civilization; an ancient evil
The broadcast interview of a young computer prodigy attracts the attention of aliens aboard an interstellar trading ship. The kidnapping of Tommy (and his cat) begins an adventure among the stars: a coming of age story entangled with computers, and faster-than-light travel.
On board the starship, Tommy meets a crew of humans, descended from peasants, priests, and soldiers taken from Earth a thousand years before, slaves to the seldom-seen aliens, the Nesu, inhabiting the upper third of the ship.
Tommy is expected to replace the ancient and failing computers on the ship with computers taken from Earth, beginning with the long-dead missile controller, without which the ship is defenseless.
But the Nesu are themselves refugees from another alien civilization that, fifteen hundred years before, destroyed the Nesu home world and now block all scientific advancement in the local arm of the galaxy.