Alvin, from the enclosed utopia Diaspar, seeks exitement elsewhere - coming to Lys, a different sort of utopia, and then finds an abandonned spaceship. Even though he risks the return of the Invaders, to escape the lingering death of isolation, he travels to the stars seeking enlightenment about his world and the way it came to be.

Magazine appearance in Startling Stories November 1948, and first in book form in 1953 from Gnome Press. I prefer the 1956 expanded version The City and the Stars for its poetry / skill of language - but this original version (same plot) holds up on its own.