chunk: Hoping to master the "zone of force", Seaton, Crane, and their wives travel from planet to planet of the 'Green System', in search of those already skilled in its use. Initially they encounter the Dasorians, an amphibious species of humanoid, who direct them to the Norlaminians, who possess full control of both matter and energy. A much larger successor ship, the Skylark Three, is built and equipped on planet Norlamin, where Seaton at first explores the Fenachrone's world, then orders the Fenachrone to abandon their conquest. Upon their refusal, Seaton destroys their reconnaissance spaceships, and then their home planet, killing all the Fenachrone except a colony led by one of their leading scientists. Equipped with a Fenachrone spaceship, DuQuesne also survives, but leads Seaton and the Fenachrone to presume his death. Increasing his technology still further, Seaton pursues and destroys the Fenachrone colony; but does not discover DuQuesne.