It tells the story of a young man, Kirth Gersen, who sets out to track down and avenge himself upon the first of the Demon Princes, the five arch-criminals who massacred or enslaved nearly all the inhabitants of his colony world when he was a child.

The antagonist of the book was originally known as Grendel the Monster and was subsequently renamed Attel Malagate for the novel version.

By now, Gersen has encountered two of Malagate's chief henchmen, whom he saw earlier at Smade's Tavern: Tristano the Earthman, and Sivij Suthiro the Sarkoy.

He has also deduced that Malagate is not, as widely assumed, human, but rather a "Star King", a member of a species that can rapidly evolve in a few generations to resemble (and strive to outcompete) what they view as the most successful race.

Through a combination of detective work and good luck, he traces her to a secret base belonging to Dasce.

Dave Langford reviewed Star King for White Dwarf #99, and stated that "The revenge plot is banal in the extreme, but the pace is headlong and it's impossible not to admire the backdrop.