The story develops by setting representatives of the sentient species at war with each other in a microcosm: a strange floating island in an isolated sea. A quick acid test will determine the quality of each culture by seeing who will survive the next few days in the most desperate of circumstances.

At stake are not only the lives of the people immediately involved, but the survival of a planetary culture, and other similar worlds beyond.

The Parahuans, old enemies of the Federation and losers in a previous clash almost a century before, have returned secretly to certain water planets of the Hub. They plan to conquer those planets, expanding their empire and redeeming themselves for their earlier defeat. Only one factor prevents them from launching a new war of conquest: The leaders are split into two factions at odds with each other over whether a new war...