Because matter in Egg, a neutron star, is vastly more dense than on Earth, reactions occur much faster. The Cheela, the star’s inhabitants, are about as heavy as humans though they are the size of sesame seeds; the average Cheela life span is about forty-five minutes, a generation about fifteen minutes. Egg’s great gravitational forces require protective asteroid masses around the human exploring vessel in order to compensate for changes in force directions.

When an engine directing one of these masses begins to fail, the humans have five minutes to live, but the Cheela have one third of a lifetime to rescue them. This emergency allows a full development of the unique interactions that are possible between the Cheela and the humans. Minutes after the rescue, a starquake occurs, instantly reducing the diameter of the star and destroying Cheela civilization.

While a dark age of Cheela civilization develops on Egg, other Cheela stranded in space attempt to devise ways of returning to the surface without the landing platforms necessary in superhigh gravity. In this process, they borrow and destroy the asteroid which the humans need to return to their mother ship, leaving the humans with no means of escape before their food runs out.

During one human day, or about ninety-six Cheela generations, the Cheela and the humans find ways to cooperate in dealing with these crises.

Senior Scientist at the Hughes Research Labs and a pioneer in gravitational astronomy, Forward writes science fiction that is particularly satisfying to readers interested in technology. He extrapolates from current theory, and he explains machinery and phenomena in technical detail. He includes in a technical appendix references to actual works in his specialty. The result is science fiction that might someday turn out to be science fact.