On the planet of the star Lalande 21185, known to Terrans as Ormazd, the dominant humanoid species is organized into hive societies much like those of Earth's ants and bees. In each community a hyper-fertile queen and a handful of male drones are responsible for reproduction, while all other tasks are performed by sterile female workers. This status quo is disrupted by the arrival of the Paris , an exploratory spacecraft of the Viagens Interplanetarias , Earth's space authority. Its mixed crew of socially equal and universally fertile males and females opens up other possibilities to the natives, and particularly to Iroedh, a scholarly worker from the community of Elham. Her own antiquarian research leads her to the conclusion that Ormazd's society may once have been like Earth's. Her peers, however, are only interested in ferreting out the Terrans' technological secrets for possible military use. Iroedh, by making friends with Winston Bloch and Barbe Dulac, two of the newcomers, ironically finds herself in a better position to do this than her more self-interested comrades.
Hoping to save Antis, a condemned drone for whom she harbors platonically romantic feelings, Iroedh uses her new friends first to effect a rescue and then to intervene in Elhamni politics to reverse his death sentence. The second effort backfires, making her, Antis and their allies fugitives. Hunted by both the Elhamni and the outlaw band of the rogue drone Wythias, who is intent on gaining Terran weaponry, they get lost in the wilderness and come near to starvation. To survive Iroedh is forced to abandon her vegetarian worker diet and eat meat, which is deemed poisonous to all females except queens. Its actual effect on her is to cause her to mature sexually, making her a queen herself, though one without a community to rule. She and Antis become lovers. Afterwards, still pursued by Wythias' band, the four succeed in reaching the Oracle of Ledhwid, a neutral power in the midst of the warring communities. To their surprise, the current occupant of the Oracle's office proves to be another alien, Gildakk from the planet Thoth in the Procyonic system, the sole survivor of an earlier expedition.
With Gildakk's aid the rogue drones are fought to a standstill and then made allies by demonstrating in a parlay that Iroedh has become a functional female; Gildakk points out that if other workers follow her example all the drones can have mates of their own. Wythias murders Gildakk in an attempt to preserve his authority, and is in turn killed by Barbe. The other drones take Iroedh and Antis as their new leaders. The reconstituted force then returns to Elham to aid in its defense against the hostile community of Tvaarm, which has just launched a long-expected invasion. The government that outlawed Iroedh and Antis is overthrown, and the combined force of their drones and Elham's warriors defeat the enemy. A social and political revolution ensues in Elham, and Iroedh and Antis accept appointment as representatives of the Viagens Interplanetarias to the city-states of Ormazd.