"The Sun Saboteurs" is a 1961 science-fiction novel by Damon Knight, published as an Ace Double, with the other side being "The Light of Lilith" by G. Mcondald Wallis. In 1961, Ace Doubles were still commonly Westerns or Mysteries, so this was one of the earlier examples of science-fiction in the format. It is also one of Damon Knight's first works. It is also short, even for an Ace Double, coming in at under 100 pages.
This book is also a masterpiece of science-fiction, especially considering its relatively early publication date. My experiences with Ace Doubles has led me to believe that they are usually good, or at least solid, but I would say this book qualifies for greatness. It has a unique concept, and manages to illustrate it deeply in 100 short pages.
It is some time in the intermediate future, and due to a series of unspecified disasters, earth has regressed from a high technology level to something a little above a dystopia. Or at least, that is how people describe it. The protagonist of the story, Lazlo Cudyk, lives on an alien planet, in a ghetto called "The Earth Quarter", where he is friends with (among others) a Chinese tea shop owner and a Greek Orthodox priest. The planet is home to a race called the Niori, sentient insectoids with porcelain shells and glowing eyes, and a very high level of civilization. The Niori, and the other sentient races of the galaxy, allow human refugees from earth to settle among them, despite a major problem: the Niori, and every other high technology race in the galaxy, have no understanding of violence or deception. That humans sometimes do strange or unpredictable things is something they notice, but barely consider important.
As for the human population, most of them face their situation of declining fortunes, exile, and placement among a much greater civilization with something like melancholy acceptance, but some react with anger, and one group with fascist tendencies wants to destroy all alien life and make the Galaxy for humans. Although totally technologically outmatched, their advantage is that no galactic civilization has weapons beyond a stasis field or the desire to use them. The leader of the fascists, a man named Rack, starts by harassing and bullying other humans in a type of spy or espionage drama, and ends with a weapon of mass destruction powerful enough to destroy stars (thus the title). The plot of the book involves finding out whether the aliens will be able to counter Rack, while the drama of the book follows Cudyk and his friends as they face the bleak fact that human nature seems to be doomed for violence.
What is so masterful about this book is that it gives us a texture of the story, the psychological struggle of a post-peak humanity, the background of galactic history and the advanced civilization that humans live among, manages to work in the espionage action on the ground, and the battles in space, and come to its conclusion, all in 100 pages. There was a few points at the beginning where I had trouble catching up with what was going on, but the story quickly got me involved, and kept me paying attention until the end. The story also had an obvious social and political message, and just as in The Rithian Terror, Damon Knight gives us a convincing story where humans are the villains, but it felt like it came naturally, and nothing was forced. This book is an excellent mix of concept, plot and characterization, and what flaws it does have come from the need for shortness in the Ace Double format.