Flandry, here a captain, undergoes a series of adventures: He is abducted by the Scothians, an alien race hoping to invade the Terran Empire; rescues the Emperor's kidnapped granddaughter; meets Aycharaych, his nemesis in league with the Merseians; and investigates a previously unencountered alien race that has invaded the distant colonial world of Vixen.

Captain Dominic Flandry, a naval intelligence officer for the declining Terran Empire, becomes involved with an alien kidnapping, the sacking of Fort Lone by barbarians, and assorted alien spies