A common theme in the stories is of how the apparent weaknesses and inconsistencies of living beings are actually the strengths that bring about the killer machines' eventual defeat.

The second story, "Goodlife" (1963), introduces human traitors or collaborators who cooperate with the Berserker machines to stay alive for a little longer.

A similar premise, though on a much smaller scale, was previously introduced by Walter M. Miller, Jr., in the 1954 short story "I Made You", described by reviewer N. Samuelson as "A pure 'sorcerer’s apprentice' sketch, about a war machine on the moon which kills anyone who comes within its range, including one of its programmers, because its control circuits are damaged.

The most common Berserkers are large spherical interstellar spacecraft, heavily armed and armored, equipped with self-replicating factories, and capable of producing numerous scout craft, foot soldiers, and other weapons of war.

Those videos had recorded slender, fine-boned beings, topologically like Solarian humans with the sole visible exception of the eye, which in the Builder species was a single organ, stretching clear across the upper face, with a bright bulging pupil that slid rapidly back and forth.

[3] In most of the ancient Builder graphics, no matter how elegantly enhanced, the berserkers' creators showed as hardly more than stick drawing of orange glowing substance.

Now for the first time in history it was plain to Solarian eyes that that orange color and brightness were the result of some kind of clothing, the exposed skin being a dullish yellow where it showed on the face, the four-fingered hands, and across part of the chest.

They are incapable of direct aggression, but they do possess one special power, a telepathic ability to speak to other sentients across the stars, a method of communication that the Berserkers cannot spy on.

The first stories in the series are related by an individual Carmpan, the "3rd Historian", who seeks to chronicle life in the Galaxy and the struggle against the Berserkers.

Homo sapiens, referred to as "Earth-descended" or "ED" Humans, or as "Solarians", is the only sentient species aggressive enough to counter Berserkers.