Pierson's puppeteers strange three-legged two-headed aliens have discovered an immense
structure in a hitherto unexplored part of the universe. Frightened of meeting the builders of
such a structure the puppeteers set about assembling a team consisting of two humans a
puppeteer and a kzin an alien not unlike an eight-foot-tall red-furred cat to explore it.
The artefact is a vast circular ribbon of matter some 180 million miles across with a sun at
its centre - the Ringworld. But the expedition goes disastrously wrong when the ship crashlands
and its motley crew faces a trek across thousands of miles of the Ringworld's surface.
