Amid escalating conflict between Earth and mysterious alien Outsiders, massive armadas from both sides are set to meet in what looks to be an evenly matched battle. Bob Carson, the pilot of a small one-man scout ship blacks out while engaging with an Outsider counterpart. When he awakens, he finds himself naked in a small enclosed, circular area about 250 yards (230 m) across. In the distance is an Outsider, which Carson labels a "Roller" because its form is that of a red sphere about 1 yard in diameter with several dozen tentacles.
Carson hears a voice in his mind that identifies itself as an evolved intelligence that has decided to intervene because the upcoming war would utterly destroy one side and hurt the other so badly that it would not be able to one day advance into an evolved intelligence like itself. This Entity therefore chose one individual from each species to fight in single combat. The loser will doom its kind to instant extinction. Carson and his opponent discove