Excellent Asimov classic from the 50s.
The Horsehead Nebula region of the galaxy was divided into a large number of smallish aristocratic nations, until they were all suddenly overrun by the banally named Tyranni about a generation before the story is set. The old royal families have been left in place in a ceremonial role; the hero of The Stars Like Dust is the son and heir of the titular ruler of one of these planets. Biron Farrill is studying on Earth - largely ruined in an ancient nuclear war - when his father dies, executed for treason by the Tyranni. An apparent attempt on his own life leads him to flee back to the Horsehead Nebula, to the palace of the Hinriads on the planet of Rhodia. A series of adventures follow, which even at the time must have seemed derivative, ending with a stupendous discovery which should mark the end of the Tyranni.
