After the Big War had left the Terran Federation in tatters, ten thousand military refugees from the losing side, the System States Alliance, fled thousands of light-years beyond the boundaries of the Federation to escape pursuit and establish a new life. There they discovered a small star cluster and colonized an earth-like planet the named Excalibur. By the time of Space Viking the former refugees had colonized a dozen worlds, which the called the Sword-Worlds, the planets having been named after legendary swords from ancient Terran tales. In their isolation, the Sword-Worlds developed a system of planetary feudalism while still managing to retain much of the former Federation's technology, including space travel and contragravity.
Things did not fare so well in the Old Federation; formerly civilized planets decivilized into ruination and barbarism. Only a dozen or so civilized worlds retained the culture and technology of the former Federation. When the Sword-Worlders discover that the Federation has collapsed, they return in force to roam and pillage the wreckage. They are given the name Space Vikings by their victims. For the next three hundred years the Space Vikings raid and plunder the poorly defended Neobarbarian worlds at their pleasure.
Lord Lucas Trask of Traskon is no admirer of the Space Vikings and despises their parasitical forays into the former Federation, both for the destruction and death they bring with them and because they take the best and brightest men away from the Sword-Worlds. Then a madman murders his wife on their wedding day and leaves on a spaceship for a Space Viking raid into the Old Federation. Trask trades his fiefdom for a second ship, vowing to hunt dow the killer Andray Dunnan. Lucas Trask is forced by the enormity of his task to raid worlds for both material and intelligence on his enemy at the risk of becoming one of the very Space Vikings he so much deplored before his wife's brutal death.