The story follows Nick Appleton, a low-class Old Man worker who becomes a subversive to the system, and Willis Gram, the Unusual ruler of the Earth.

Separately, resistance leader Thors Provoni has left the planet to find an ally to the Old Men, finally returning with an alien from far away in space.

A resistance figure known as Thors Provoni, who long ago went deep into space to find help to put the Old Men back in power, has finally announced his impending return.

Nick Appleton, a lowly tire regroover, is further disillusioned with the system after his son Bobby fails the civil service examination, as the test is geared toward only passing New Men and Unusuals.

This in combination with his son's exam failure radicalizes Appleton, and he falls for Charlotte "Charley" Boyer, a sixteen-year-old subversive who distributes Cordonite resistance literature together with her abusive alcoholic boyfriend.

The nature of the Frolixian species is to absorb and then consume, having peacefully eliminated all other animals on their home planet through sterilization to facilitate their expansion process.

Gram fears the return of Provoni and turns to a prominent New Man scientist, Amos Ild, to foresee the future.

[3] A French translation, Message de Frolix 8, was published by Éditions OPTA [fr] in their Anti-mondes collection, for presenting the best of science fiction.

[15][2] Other themes include freedom of choice, commitment to a cause, and the involvement of other powers in human affairs, as the Frolixian's motives are often ambiguous.

[2] Mackey called Frolix 8 "in a sense a throwback";[9] Warrick said that themes common in Dick's novels from the mid 1950s to 1960s, like violence, economic exploitation, media manipulation, totalitarianism and loss of morals, were present here as well, though they only "stir[red] feebly.

"[2] Andrew M. Butler said it was dull in comparison to Dick's other novels of the time, and said that "dystopia meets space opera is all you can say about it".

[26] A contemporary review from the SF zine Luna Monthly praised Frolix 8 as a "readable and entertaining" book, which while having many "far-out ideas" had "more logic and cohesion" and being easier to follow than most of the author's works, calling its plot well structured and noting its scene and POV shifts to be typical of him.

[27] Darrell Schweitzer, in the Science Fiction Review in 1978 called it "not top drawer Dick", but said that even "his middle drawers are more interesting than most",[28] while a review in the British SF magazine Vector called it "a lively, entertaining book, abrim with ideas", that presents "no solutions to the various moral dilemmas" portrayed within.

[16] The plot received criticism, particularly for its perceived lack of originality compared both to general SF and Dick's other works.

[9][12][2] Mackey called the plot thin compared to early 1960s books from Dick, with some of the weaknesses of more standard SF conventions appearing.

[12] Michael Rogers, writing for the Library Journal, described the novel as being "couched in the usual sf trappings", though noted it would appeal to those who were already fans of Dick and Blade Runner.

[2] Andrevon expressed a similar sentiment, saying that Dick had "merely systematically and inspiredly reused schemes he had once used infinitely better" in other works.

[31] Valerio De Angelis and Umberto Rossi also compared it to the works of SF author A. E. van Vogt; they said that while it had a poorly constructed plot, it was at times an excellent satire of TV commentary.

[11] While describing it as "not successful", Warrick said it contained "passages rich with interesting ideas and characters", which allowed for a better understanding of Dick's creativity.