Krip Vorlund, one of two narrators, is a young human who is a Free Trader, or entrepreneur, on a starship. The crew lands on the planet Yiktor, which is circled by a moon that periodically shows three rings. Yiktor is home to humans and Thassa, an ancient nomadic race with amazing powers over animals. The Thassa live in isolation from humans. They are governed by powerful telepaths called the Old Ones.
Maelen, the second narrator, is a Moonsinger of the Thassa, a kind of alien shaman. When the three rings are in conjunction, she gains special powers through singing, exchanging bodies with animals, and sharing minds with other Thassa. Comrades-in-fur, the animals who speak with the Thassa, perform for audiences and exchange bodies with the Thassa. The two narrators present their differing perspectives on the action and plot, and the reader sees that Maelen and Vorlund do not fully understand each other.
Gauk Slafid works for an interplanetary corporation called the Combine. The corporation is banned from trading weapons with primitive planets such as Yiktor, but Slafid illegally plots with Oskold, a local lord, to use off-world weapons. They are desperate to hide their nefarious actions from both the Combine and the humans on Yiktor. Vorlund is a pawn in this plot involving interplanetary politics, money, power, and an unknown culture.
Maelen uses her Moonsinger’s skills to help Vorlund survive a manhunt by placing his mind in an animal. Vorlund runs wild and frightened as an animal and struggles to keep his sense of being human. Maelen has broken the highest laws of the Thassa to help Vorlund, and her disobedience results in loss of her Moonsinger status. She must live, moreover, in an animal body, without any immediate hope of returning to the Thassa. Although she thinks the Old Ones are punishing her too harshly, she accepts their judgment.
Vorlund also suffers. His apparent corpse has been consigned to outer space, so he is placed in a Thassa body and permanently separated from his real physical body. Vorlund and Maelen leave Yiktor together and hope for a better future.