On one of those moons, Alex Ligon, scion of a great interstellar trading family, has turned his back on the family business in favor of mathematics. He has developed an incredibly accurate new population model. But when he extends the model a century into the future, it predicts the complete destruction of the human race.

On another moon, the search for Extraterrestrial Intelligence continues, undaunted by generations of failure. To her amazement, a new recruit finds a signal -- one coming from outside the solar system.

And in this new retreat on a minor moon of Saturn, a genius collects weapons from the Great War -- only to find one set to destroy the Sun.