Nominally a tale of Comet Jo’s coming-of-age, his education into galactic society (and as such can be considered a mini-Bildungsroman), his efforts to deliver an important message to Empire Star, and the attempt to bring an end to slavery, the story has several layered loops of events which run back upon themselves—and the concepts, layering, and ordering of the events are as important as the story itself.

He has spent his entire life in a "simplex" society on Rhys, a satellite of a Jovian planet orbiting Tau Ceti.

(At first it might seem that "simplex" means "simple" or "unintelligent," but after Jo's encounter with the "Geodesic Survey Station" at the latest, it will be clear the notion is much more complicated.)

The first is quickly dying and asks Jo to bring an important message to Empire Star moments before passing away.

Jo quickly leaves Rhys in an attempt to deliver the message to Empire Star, and on his journey he meets several other characters along with a race of creatures known as the Lll.